These are stories
from the
last few weeks...
August 24, 2010: All That Glitters is
not Gold
The grassland outside my study window
has taken on an almost uniform
yellow color, as have most of the fallow fields in the area. Even the
most disinterested person usually knows goldenrod when he or she
encounters it—perhaps even more than the ubiquitous Queen Anne’s lace.
About 100 perennial species make up the goldenrod family, most being
found in the meadows and pastures, along roads, ditches and waste areas
across North America.
The botanical name of this remarkable
plant, Solidago, means “to make
whole” and it has been used as a healing herb since ancient times. For
Native Americans, it was a staple medicine, as nearly every tribe had
at least one variety close at hand. Called “sun medicine,” it was used
to treat everything from wounds and fevers to rheumatism and toothache.
It was also used as a charm, smoked like tobacco, woven into baskets,
burned as incense, and made into a dye.
Learning that goldenrod sap contained
natural latex, Thomas Edison
decided to see if he could use it as a source of rubber. He produced a
resilient, long-lasting product that Henry Ford made into a set of
tires for his own personal automobile. From the common weed that grew
to an average height of 3-4 feet and contained 5% yield of latex,
Edison produced a hybrid that grew to 12 feet and yielded 12% latex.
His research was turned over to the U.S. government when he died in
1931, but the project was dropped and never revived, even when rubber
became almost impossible to obtain during World War II.
Probably due to its prominent, golden
yellow flower heads in late
summer, the goldenrod is often unfairly blamed for causing hay fever in
humans. The fact is that the pollen causing these allergy problems is
mainly produced by the ragweed that blooms at the same time as the
goldenrod, but is wind-pollinated. Goldenrod pollen is too heavy and
sticky to be blown far from the flowers, and is thus mainly pollinated
by insects. To get the pollen in your nasal passages, you’d have to
sniff a flower close to your nose. Frequent handling of goldenrod and
other flowers, however, can sometimes cause allergic reactions.
A common sight among any cluster of
goldenrod stems is the presence of
round or elliptical swellings called galls. These can be caused by
fungi and viruses, but most commonly by insects; for example, when
certain flies and moths lay eggs on a plant stem or leaf, their larvae
hatch and tunnel into its tissue where they feed on the plant's cells.
The plant reacts by producing a tumor-like growth that houses and feeds
the grub.
There are three different insects that
use goldenrod in this fashion:
the apple gall fly, the elliptical gall moth, and the rosette gall
midge. This last one--a miniscule fly--lays its egg in a leaf bud and
the presence of the grub somehow keeps the stem from growing and
elongating, resulting in a thick tuft of leaves usually at the top of
the main stalk. The other two insects cause ball-like galls to form on
the plant stem that remain through the winter.
Although goldenrods are easily
recognized by their showy arrays of
hundreds of bright yellow flowerets, the various species are often
difficult to distinguish. Canadian goldenrod is our most common and
weedy type. There is some experimental evidence that this species
inhibits the growth of other plants by exuding chemicals through its
roots, although reportedly these results were obtained in the
laboratory and have not been proven in the field. The main problem it
causes is that its root system is made up of creeping rhizomes that
cause the plants to cluster, forming dense colonies that may crowd out
other plants.
It is virtually impossible to
eliminate this species from an area, but
removing seedheads and treating with an herbicide, not just once but
repeatedly as new plants appear, will hopefully create a situation
where diverse competition will hold it in check. Perhaps this is for
the best as some authors say that goldenrod is one of the most valuable
plants on the continent to feed our pollinators. Its high protein
pollen and tremendous nectar yields give many species of bees and wasps
their last good feed of the season.
----------------------------------------------------
August 17, 2010: Swallow Tales
Swallows and martins are members of a family of songbirds that are
known for feeding on the wing. They snatch up flying insects, selecting
the larger ones (regrettably, mosquitoes are somewhat down on their
preference list), and avoiding stinging insects such as bees and wasps.
Their flight may be fast and involve a rapid succession of turns and
banks when actively chasing fast moving prey, or slower and more
leisurely as they fly in circles, alternating flapping with gliding to
catch less agile victims.
We have six species in Wisconsin and they can be separated into two
groups—those that nest in cavities and houses, and those who construct
nests of mud that they plaster beneath overhangs, either natural or
manmade. The Northern rough-winged and bank swallows are fairly common
plain brown birds with light underparts and forked tails that nest in
cavities near the water, usually in burrows that may be up to two feet
in length. These birds forage in flight over water or fields, flying
low to scoop up flying insects, and both migrate to the Gulf coast and
south to Central America in winter. The Northern rough-winged swallow
derives its name from the outer wing feathers, which have small hooks
or points on their leading edges.
The tree swallow will nest in a natural or artificial cavity near water
but will also readily use a nest box, including one built for
bluebirds. We had a pair some years ago in a birdhouse near the
farmyard, only to have house sparrows chase them off, never to return.
The adult tree swallow has iridescent blue-green upperparts, white
underparts, and a very slightly forked tail while the female is more
greenish and less colorful.
The largest of the family is the purple martin, with an average length
of 8 inches from bill to tail. Adult males are entirely black with
glossy steel blue sheen, and a slightly forked tail while females and
young are less showy. (Within the family, the name "martin" tends to be
used for the squarer-tailed species, and the name "swallow" for the
more fork-tailed species.)
Purple martins catch a variety of insects from the air but fly
relatively high, so mosquitoes do not form a large part of their diet
despite many claims to the contrary. They make their nests in cavities,
and in many places they are almost entirely dependent on man-made
housing. The birds suffered a severe population crash following the
release and spread of European starlings during the last century, as
the more aggressive starlings and house sparrows took over many of the
martins’ nesting sites and killed their young.
Cliff swallows often breed in large colonies. They once placed their
conical mud nests beneath cliffs, but now usually build them under
overhangs of man-made structures such as barns, bridges, and the like.
The gourd-shaped nest is a covered bowl made of mud pellets, with a
small entrance tunnel on one side. A neighbor’s barn down the road is
host to dozens of these birds, and they often greet us with great
swoops and acrobatics as we pass. These are also the famous swallows
whose return every year to the Mission San Juan Capistrano from
Argentina is celebrated with a festival, although in recent years, the
swallows have been nesting in the Chino Hills to the north.
Probably the most frequently observed member of the family is the barn
swallow, a bird that often reminds me of a butterfly with its lovely
colors and long tails. I was amused to note that the first three
internet sites listed after a Google search were concerned with getting
rid of these birds despite their desirable qualities, as they are so
comfortable with building their nests near humans that they invade
porches, patios, and any available similar area. Not only do they
plaster their mud nests onto the building siding, dropping bits on the
floor below, but their chicks deposit their droppings there as well—a
mess not often welcomed by their human neighbors.
The adult male barn swallow is about seven inches in length including
its tail. It has steel blue upperparts and a rufous forehead, chin and
throat that are separated from the off-white underparts by a broad dark
blue breast band. The outer tail feathers are elongated, forming the
distinctive deeply forked "swallow tail", and there is a line of white
spots across its outer end. The female and juveniles are less colorful
and have shorter tail feathers. It is a fact that males with longer
tail feathers are generally longer-lived and more disease resistant,
and are more attractive to females.
One characteristic of the barn swallow that we find particularly
intriguing is that it seems to “play”. We have watched one carry a leaf
high into the air, let it go, and then snatch it as it flutters down
before carrying it aloft again. After a bit, another bird will swoop in
and grab it to join in the game. Once several were playing with a leaf
on the shed roof, allowing it to slide down the slope before flying
down to capture it. Wouldn’t it be fun to know what goes on in their
minds at such times?
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August 3, 2010: Bob..White!....
We have had a new family in the area
the past few weeks. Where they
came from is a bit of a mystery, as I’ve asked around among our closest
neighbors and no others have even seen them, let alone had any hand in
introducing them. In past years we have heard the distinctive whistle
perhaps two or three times —“bob-White! bob-White!”, but the birds
seemed to leave as quickly as they arrived and we saw no more of them.
We understand that these birds are notoriously difficult to see,
keeping hidden in tall grass or standing crops, and reluctant to fly,
preferring to sneak away instead. Even when flushed, they keep low and
soon drop back into cover.
This time, however, it was a family—at
least 14 mostly grown chicks and
2 adults. I saw them first parading down the road in a line (and so was
able to get a good count), and later several times around the farmyard.
Then one morning I was surprised to see half a dozen perched on the
railing of our north deck, while the others explored the garden below.
Since then they have again visited the porch, perhaps to get an
elevated view of the premises, and we wonder at their tame behavior.
The Virginia quail is a native “game
bird”— a designation given to
those species that are hunted for sport or food, including pheasants,
quail, grouse, and several other less well known types. It is more
commonly called northern bobwhite or bobwhite quail because of its
characteristic call, and its brown, speckled body weighs only 5-6
ounces. The male is distinguished by having a white chin and upper
throat and a white stripe running from the bill to the back of its
black head while the female is a little larger in size, and has tan
collar, eye strips and undersides.
Quail are bred and kept as poultry in
some parts of the world both for
eggs and meat. The common quail of Europe was previously much favored
in French cooking, but quail for the table is now more likely to be
domesticated Japanese quail. These are commonly eaten complete with the
bones, since these are easily chewed and the small size of the bird
makes it inconvenient to remove them. The eggs of quail are considered
a delicacy, and are sometimes used raw in sushi.
Northern bobwhites can be found
throughout the eastern United States
west to the Great Plains, usually in hayfields, pastures, prairies, and
oak savannah. They forage in nearby row crops and small grains such as
millet, wheat, milo sorghum, and other grains; however, quail are also
fond of weeds such as ragweed, partridge peas, and various vetches.
Grasshoppers serve as the primary diet of young bobwhites and are eaten
by adults as well. Shrubs, brush piles, and hedgerows are used
for hiding and roosting and this woody cover is vital for winter
survival.
Quail travel in coveys (groups) of
five to 30 birds during the
non-breeding season, but in March and April, pairs begin to form. Nests
are established on the ground hidden in dense underbrush, but usually
within 20 yards of openings such as fields or roads. A female quail
will lay one egg a day until twelve to sixteen eggs have accumulated
and then will brood them for about 23 days. If the first clutch of eggs
is unsuccessful, a breeding pair (perhaps the same pair or the female
may accept a different mate) will attempt to produce another clutch.
When the eggs hatch, chicks are up and running almost immediately and
will leave the nest within 24 hours, although they often stay with the
adults through fall and winter.
Northern bobwhites were abundant
historically in southern and central
Wisconsin, but intensive market hunting in the late 1800s and
subsequent changes in agricultural practices have resulted in dramatic
declines. They are now concentrated in the southwestern part of the
state, with only scattered populations elsewhere. Whistling bobwhite
quail route surveys have been conducted since the summer of 1949, and
the number of calling males per stop has decreased steadily, with a
spectacular drop in 2007 to 2009 of 74%. Winters temperatures were
below average with above average precipitation for those winters with
record rainfalls at the peak of hatching. A more significant long-term
factor is thought to be the changes in land use with continued losses
of grasslands.
The effort to save the species has
taken two forms: bobwhites are being
propagated in captivity in large numbers for release on hunting
preserves and natural areas, and considerable work is being been done
to restore the weedy, protective, and food-rich "edges" that the quail
prefer. In the first half of the 20th century, smaller farmers had
gardens and crops divided by overgrown hedgerows and fencerows that
provided close cover for birds. Large-scale agriculture cleared much of
the land, but now Conservation Reserve Programs (CRP) and
state-designed programs are putting large areas back into suitable
habitat. Also, Quail Forever has over 100 chapters in 25 states that
are working hard to encourage quail habitat projects such as tree
thinning and burning.
We hope that at least a few of the
family will survive to nest next
spring, and that quail will take up residence in our valley. We will be
listening for the bobwhite call come spring.
___________________________
July 27, 2010: The Not-so-Lowly
Milkweed
I used to think that milkweed was
little more than a nuisance weed,
sprouting where I did not want it, displaying blah-colored flowers, and
generally being of little use except as food for the monarch
caterpillar. I have since revised my opinion, as I have found
that even the common variety has a heavenly smell and its flowers are
complex and unique. At one time or another I have found specimens of at
least seven species here on the farm, each of them displaying the
characteristic flower made up of 5-parted cups crowned by five
swept-back petals. These are always arranged in clusters,
sometimes held erect, other times drooping on long stems.
All of the milkweeds, as every kid
soon learns, have a sticky white sap
in their stems and leaves. This sap has been used to treat various
ailments through the centuries; in fact, the plant’s Latin name,
Asclepias, was taken from Aesculapius, the legendary Greek god of
medicine. The treatment success rate of these doctorings is pretty
vague but the practices of applying the sap directly on a wart and as a
natural remedy for poison ivy are still common.
Milkweeds may cause mild dermatitis in
some who come in contact with
it, and analysis has shown that they contain alkaloids, latex, and
several other complex compounds including cardenolides, a type of
steroid, some of which are toxic and may seriously affect the heart.
The latex contains about 1 to 2% natural rubber, and unsuccessful
experiments were conducted by both Germany and the United States during
World War II in an attempt to use it as a substitute for tropical
rubber. After the War, these efforts were abandoned until Standard Oil
of Ohio became involved with milkweed in the late 1970s predicting that
billions of barrels of synthetic crude oil could be recovered from the
biomass of milkweed. Milkweed was grown like hay—it was cut, dried,
baled, and a crude oil substitute extracted—but they found that the
price was too high and the yield was too low.
Finally, in 1987, the Natural Fibers
Corporation was organized with two
goals—to grow milkweed, not as a source of crude oil, but to process
its pods to recover salable floss as a fill for jackets and bedding.
The milkweed filaments from the pods are coated with wax, and have even
been thought to be superior to down feathers for insulation. During
World War II, over 11 million pounds of milkweed floss were collected
in the United States as a substitute for kapok in life preservers
(kapok was the fluffy, yellowish fiber used for stuffing at that time
that was harvested from the seedpods of a tropical tree) and the boys
and girls from Wisconsin schools alone collected 283,000 bags of
milkweed fluff. This effort has led to a commercial product called
Hypodown that is used in comforters and pillows in the bedding
industry. This is a combination of white goose down and milkweed that
is touted to trap and suppresses the dust and dander that plague people
with allergies.
Pollination in milkweeds is
accomplished in an unusual manner, as the
pollen develops in "pollen sacs" that grow in pairs and are situated in
the slits of each flower. When an insect visits the flower, its feet or
mouthparts often slip into one of the slits and make contact with these
sticky objects. The sacs with the pollen inside are then carried to the
next plant and trapped in its slits allowing cross-pollination to take
place. The flower cluster then develops into a number of elongated pods
holding overlapping rows of seeds tucked inside. Each seed is equipped
with white silky filament-like hairs and is carried off by the wind as
the pods dry and split open.
Reportedly, most animals and insects
avoid eating milkweeds because of
their bitter taste, but some beetles, moths, and true bugs (besides the
highly publicized monarch butterfly) have adapted to feed on the plants
despite their chemical defenses, and even seem to gain protection from
predators in this way. Interestingly, all of these seem to be brightly
colored with orange and black, and some authorities suggest that the
colors are signals warning of their bad taste. It is also true that
some other plants actually benefit from their proximity to a milkweed
as it repels some pests such as wireworms. These are the larvae of a
variety of click beetle species, many of which attack a variety of
plants and are serious agricultural pests.
Regardless of its commercial value, we
enjoy half a dozen species of
milkweed on the farm. There is the bright orange butterfly weed, the
showy purple milkweed, the poke milkweed with its drooping clusters of
whitish flowers when few other things are blooming, the several green
types that seem to appear and disappear for no reason, and the whorled
milkweed, a delicate plant with radiating linear leaves and small
clusters of white flowers up the stem. Other types grow elsewhere in
various habitats, most notably the swamp milkweed that has lovely
purple blossoms. The next time you see one of these beauties, take time
to appreciate its blossoms and its aroma, and examine any insects
feeding there. You may be surprised at you what you find.
-------------------------------------------------
July 20, 2010: Nests and More Nests
Even the most unobservant walker has
at some time discovered a bird’s
nest, although it is often long after the family it nurtured was grown
up and flown. Birds use nests to protect their eggs and nestlings from
predators and weather extremes, and to help keep eggs and nestlings
warm. We usually think of them as supported by tree branches, but some
birds build nests on the ground, some in bushes, while still others
attach their nests to the sides of cliffs. Barn swallows are most often
seen around barns, porches and other outbuildings, while chimney
swifts, as the name implies, favor chimneys and other man-made
enclosures. Wrens will nest in almost any cavity, from an empty
watering can to a coat pocket (as well as David’s jeans).
Nest building is thought to be
primarily instinctive as the structure
and materials of nests are very similar across a species, even when
birds are raised in isolation from others of their kind. Still, some
learning is also involved because older birds usually build 'better'
nests than younger birds (especially those in their first breeding
season). Birds can make hundreds of trips to collect materials, and
while most seem to prefer grass and twigs, some use almost anything
that they can carry—even candy wrappers, cellophane, shredded money and
barbed wire. Which of the pair actually does the building varies by
species, and in some cases, both collect materials and join in the
construction. One of the more peculiar routines is that of the male
marsh wren, which builds as many as 10 dummy nests in his territory
before the female arrives. She then makes her choice and finishes it
with a lining of soft materials.
Researchers from Ohio Wesleyan
University suggest that some birds may
select nesting material with antimicrobial agents that protect their
young from harmful bacteria. "If the fresh herbs and plant materials
that parent birds bring into the nest have a sufficient concentration
of antimicrobial compounds, they could protect the nestlings from
harmful bacteria," says researcher Jann Ichida. Ichida and colleagues
tested 12 different volatile plant materials against feather-degrading
bacteria and results showed that several types of plant materials and
extracts did in fact inhibit the growth of a number of harmful
bacteria.
Not only are the method of
construction and materials used important to
nesting success but some birds consider orientation as well. In one
study, it was found that horned larks consistently situated their nests
adjacent to and north of objects such as a tuft of grass or a rock,
thus shading them in the hottest part of the day and providing
increased daytime ventilation of the prevailing winds. In addition, the
shade may also help conceal the nest from predators.
To hold a nest together and secured in
place, birds need good adhesives
and use a variety of natural substances to do the job, including mud,
saliva, spider webs, caterpillar silk, leaf mold, and certain plant
fibers. Materials that make up the nest can be intertwined, and
sometimes are actually woven together using grass, strips of leaves,
and twigs.
Bird nests vary from a simple
accumulation of materials on the ground
to elaborate refuges in or on secluded and elevated locations. It is
interesting to note that nest construction and placement often
correlates with the ability to fly. Scrape nests that are just simple
depressions in the ground or in the leaf litter are used by turkeys,
grouse, chickens, quails, and pheasants—all relatively weak fliers.
Doves, cuckoos, herons and egrets use a bit more effort and build
simple ground nests or crude elevated nests.
More efficient fliers usually
construct nests in a bush or tree or on a
cliff or rock ledge, and young raised in elevated and cavity nests have
strong wings and chest development along with smaller legs. Some of the
most complex nests are associated with swallows, orioles and weaver
finches. The latter two groups often live in areas where there are many
predators and build their intricately woven pendant nests hung from the
thin branches of bushes and trees. Perhaps the most predator-proof
nests are those of swallows and swifts that often construct mud
structures attached to the most remote overhanging feature within their
territory.
Most birds construct a new nest for
each brood, and there is good
reason. There are at least 2500 species of blood-feeding mites and
ticks from 40 families that are closely associated with birds, and
virtually no species is free of one or another. Adults and nymph stages
of these blood feeders live in the nests or on the birds themselves,
and usually multiply rapidly, sometimes building up huge populations
that can cause considerable damage by slowing development or even
killing chicks. With this in mind, it might be wise of David to
consider retiring those old jeans that are currently holding the wren
nursery and get a new pair.
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July 13, 2010: Horns on Worms?
The sun had just set and the sky was a
palette of pastel pinks,
yellows, and purples—a sight worth savoring—and I walked out onto the
deck. I disturbed the hummingbird that was getting its sugar fix for
the night, but then another flyer took wing almost under my feet. I
ducked as it came within inches of my head but then laughed at my
reaction for it was just a moth, albeit the largest one I had seen this
year. It fluttered off before I could make identification, but its size
led me to guess that it might have been a tomato hornworm or, more
properly, a five-spotted hawk moth.
This is a large, heavy-bodied moth
with narrow front wings, a mottled
gray-brown color with yellow spots on the sides of the abdomen and a
wing spread of 4 to 5 inches. Its larvae feed only on tomato plants or
their relatives such as garden peppers, potatoes and eggplant, and
weeds such as horse nettle, jimsonweed and nightshade. Eggs are
deposited singly on the leaves in late spring and hatch six to eight
days later. The larva is white but as it grows it sheds its skin
several times, and eventually becomes pale green with white, lateral
"V-shaped" markings and a black projection or "horn" on its tail that
gives the caterpillar the name "hornworm."
Hawk moths are somewhat different from
the giant silk moths that I have
enjoyed tending in past years. The silk moths look and act more like
butterflies with their wide outstretched brightly-colored wings. Then
too, their larvae encase themselves into silken cocoons before
splitting their skins a final time and transforming into pupae. When
these hatch, the adult silk moths live only long enough to mate and lay
eggs and then die as they have only rudimentary mouthparts and eat
nothing during their short lives. The males have wide feathery
antennae, while those of the females are somewhat narrower and less
showy.
The hawk moth, on the other hand
usually has narrow forewings that are
patterned to look like tree bark, leaving any color to be displayed on
the hind wings or body where it is mostly hidden when at rest. It flies
more like a hummingbird, with rapid beating of its wings, and has the
ability to hover, a capability that has evolved only three times in
nectar feeders: in hummingbirds, certain bats, and these moths. Its
antennae are generally not very feathery, even in the males, but its
body, legs, and wings are densely covered in narrow scales that look
much like hairs. It feeds as an adult through a long tube proboscis
that it keeps curled tightly until needed and then extends to probe
deeply into flowers to reach any nectar. The larvae do not spin cocoons
but simply burrow into soft dirt and there transform into pupae,
protected only by their hard brown “skin”.
Besides the tomato hornworm (that is
often not a welcome resident in
our gardens), we have several other hawk moths in our area. The catalpa
sphinx moth is brown in color with a wingspan of about 3 ½
inches. Its larvae feed exclusively on catalpa trees and when they
mature, one can find a number of the yellow caterpillars with the wide
velvety black stripe down their backs on the ground searching for a
soft spot into which to burrow.
More common is the white-lined sphinx
moth, a more colorful insect
whose wings are marked with (guess what?) white lines, and who will
visit your petunias, phlox and other fragrant evening flowers. Take a
flashlight and walk through your garden at dusk and you very well may
see the reflections of your light in the eyes of one or more of these
lovely moths. Their larvae feed on any of the varieties of portulaca,
and if your yard is anything like mine, you will have plenty of this
around that you may know as pigweed or purslane. This is a trailing
annual weed with small yellow flowers and reddish, fleshy stems and
leaves whose joints will form roots when they come in contact with the
ground.
If my moth was a tomato hornworm, I
will have to watch my tomatoes
carefully in the coming weeks to see if they have been targeted as food
for its offspring. Soon, any resulting caterpillars will reach their
mature size of 3 to 4 inches, at which point they will drop from their
plants and burrow into the soil to pupate. Adult moths will emerge in
about 2 weeks and will mate and deposit the eggs for another
generation. These caterpillars will form pupae by early fall that will
remain in the soil all winter and emerge as moths next spring.
We find these caterpillars are easy to
control if their numbers get too
large, as their presence is obvious from the areas of devoured leaves
and they can be simply picked off. There are also natural factors that
help to control them. The egg stage and hatching larvae are often eaten
by various predatory insects such as lady beetles and green lacewings,
while the growing caterpillars are targets of a small braconid wasp.
This insect lays its eggs directly on the caterpillar and when the eggs
hatch, its larvae burrow in and feed on the inside. These mature,
emerge, and spin cocoons that appear as white projections protruding
from the hornworm’s body, and eventually kill it.
I grow plenty of tomatoes, however, so
that I can share some of the
plants with the few caterpillars that are likely to make it to
maturity. Having these beautiful moths flying around our home on summer
evenings is one of the pleasures made possible by having a big garden
in Wisconsin.
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July 6, 2010: Butterflies
Until the rain brought an end to our
lovely stretch of fine weather, it
has been difficult to walk from the porch to the road without
scattering dozens of butterflies. Painted ladies, red admirals,
red-spotted purples, and a few other species flitted about, mostly on
and above the gravel driveway. The first two species are insects that
cannot tolerate our winter conditions and either are killed or migrate
to warmer areas each fall. Then in the spring the butterflies must move
up into the state again, and often do so in large numbers. The
red-spotted purple is hardier and the last brood of the summer goes
into hibernation as larvae, pupating and emerging as adults the
following spring.
Perhaps it was the warmth of the sun
but there also was probably
moisture beneath the stones that drew them. Butterflies seem to detect
the same basic flavors as we do, sweet, sour, salty and bitter, but
have different perceptions as to what they find desirable. Manure,
urine, decaying plant wastes, and other damp debris will bring them by
the dozen, presumably to obtain certain minerals and salts that their
bodies require.
It is easy to assume butterflies are
attracted to our gardens by seeing
the bright colored flowers; however, what more likely brought them was
the perfumed invitation that the flowers were sending out. Butterflies
have very sophisticated senses of smell and taste as these are their
main windows on the world, rather than the sight and sound that we and
most other animals use. Many of the receptors are on their antennae,
the two "feelers" that all insects have on their heads and which give
them an enormous amount of information about their surroundings.
Antennae are usually segmented tubes,
moved by tiny inner muscles.
These may be covered with minute hairs, knobs, bristles, or scales that
are extremely sensitive to odors and chemicals, movements, and physical
contact. The main functions are usually smell and taste, however, and
butterflies often wave their antennae about as they "sniff" the air for
telltale scents and odors. Insects need two antennae, incidentally, to
establish direction. Tiny as they are, they can distinguish which
is receiving the stronger scent and therefore can fly toward the source.
Insects use smell to communicate,
orientate, navigate, detect humidity,
find food and water, locate suitable egg-laying sites, and identify
friends and foes. The olfactory receptors are porous pegs or cones
covered by a very thin layer of cuticle, and containing sensory nerve
cells. They can detect scent molecules in the most minute quantities
and are usually concentrated on the antennae, although there may be
some on the mouthparts as well. Butterflies and moths can be drawn to
mates over distances of a mile or two by the pheromones produced by one
or the other.
Butterflies rely on taste as well as
smell to determine whether liquids
are suitable to drink. Taste receptors are similar in structure and
function to the olfactory receptors as both detect the presence of
various chemicals, airborne in smell, and by contact in taste. Taste
receptors in insects are usually found on and around the mouthparts but
butterflies have them on their antennae and on their feet as well.
Thus, a butterfly is led to a food source by the smell, lands upon to
it taste with its feet and then probes with its feeding tube for
confirmation. A monarch butterfly's sensors have been shown to detect a
sugar solution of only 0.0003 percent strength and are more than 2000
times more sensitive than those on the average human tongue. Observers
have also determined that the taste receptors in the feet trigger an
increase in the butterfly's internal blood pressure that causes the
tube-shaped tongue to uncoil automatically.
In addition to the antennae,
butterflies have bristles and hairs
growing on their bodies and legs. Each one grows from a socket and has
a ball joint at its base that can move freely in all directions.
The socket is supplied with a network of microscopic nerve fibers that
detect and transmit any movement to the brain. Insects also are
supplied with fluid-filled chambers that are lined with tiny bristles
and contain solid granules called statoliths. As the insect moves
about, the statolith tends to remain stationary in the chamber and the
bristles on its wall detect its position, relaying information about
the insect's orientation and balance.
We have a great variety of butterflies
and moths that live in our yards
and wild areas, some with wingspans of less than an inch or so. Despite
all the fascinating complexity of their bodies, the beauty of their
wings, and their value as pollinators, butterflies are considered to be
just another delicious if somewhat elusive meal for the birds that
inhabit our farmyard.
----------------------------------------------------------------
June 26, 2010: An Accessible
Volcano Caldera
Walking around on the floor of a
volcano crater is an experience. Jets
of boiling hot water spurt into the air from holes in the earth’s crust
and gases and steam rise from fumaroles on every side. Visitors must
keep to the boardwalks that allow them to reach many of the more scenic
spots, and they are warned not to stray off the paths or risk breaking
through the thin crust that separates them from the heat below.
Yellowstone Park lies on top of an
area where hot, molten rock rises
towards the surface, and over the past 17 million years or so, volcanic
eruptions have caused the overlying land to collapse forming a
geographic depression called a caldera that is some 45 by 30 miles. The
largest violent eruption excavated the West Thumb of Lake Yellowstone
around 150,000 years ago, and the most recent lava flow occurred about
70,000 years ago. Currently, volcanic activity is visible in the form
of 10,000 geothermal vents scattered throughout the region, including
the famous Old Faithful Geyser. The Yellowstone caldera still
experiences between 1000 and 2000 measurable earthquakes a year, though
most have a magnitude of 3 or weaker. The most recent swarm, as a close
grouping of quakes is called, started after the January 2010 Haiti
earthquake and was the second largest ever recorded in the Yellowstone
caldera.
Geologists closely monitor the
Yellowstone plateau, which rises and
falls about half an inch yearly: however, from mid-summer 2004 through
mid-summer 2008, the land surface within the caldera moved upwards
significantly, with 8 inches of rise at the White Lake GPS station.
Fortunately, by the end of 2009, the uplift had slowed and appears to
have stopped, so that the U.S. Geological Survey and the Yellowstone
Volcano Observatory now state that they "see no evidence that another
such cataclysmic eruption will occur at Yellowstone in the foreseeable
future although such events are not really predictable."
Our country has done a number of
things right through the years, and
one of them was the establishment of the national park system.
Yellowstone is one of the gems of this group and contains some 3470
square miles of forests, grasslands and water (an area larger than
Rhode Island and Delaware combined), with altitudes from about 5300 to
11,400 feet. In addition to the geothermal vents, there are
approximately 290 waterfalls, 15 ft. or higher and flowing year-round,
the tallest being the lower falls of the Yellowstone River at 308 ft.
The park also contains one of the world's largest petrified forests. It
boasts 67 species of mammals, including 7 species of native hoofed
animals and 2 species of bears, 322 recorded species of birds (148
nesting species), 16 species of fish, 6 species of reptiles, 4 species
of amphibians. It harbors 2 threatened species, the Canada lynx and the
grizzly bear, and one endangered species, the gray wolf.
The animal we saw most frequently in
the park was the bison. It can be
up to 6 feet tall, 10 feet long, and weigh up to a ton. The heads and
shoulders are massive, and both sexes have short, curved horns, which
they use in fighting for status and for defense. We felt it also has a
sense of humor as we twice watched a huge animal leading its buddies in
a leisurely stroll along the center of the park road blocking all
traffic. We could imagine him saying to his cohorts, “Let’s go have
some fun with those dummies in the automobiles.” I’m sure the people in
the back of the mile-long lines of stalled vehicles could only guess
what was causing the problem.
It was surprising to see how slow was
the recovery from the 1988 fires
that affected a third of the park. Five fires apparently burned into
the park that year from adjacent public lands, but the largest, the
North Fork Fire, started from a discarded cigarette and burned more
than 410,000 acres. Many of the canyons and hillsides are still covered
with standing snags as well as criss-crossed fallen trunks and
branches, and the regenerating trees among them are only about ten to
fifteen feet high, even after 22 years. It will be many years before
the park will reach its pre-fire appearance.
Driving across the country past fields
of corn, then vast areas that
are good only to pasture cattle and finally lands where only occasional
antelopes seem to be able to eke out a living, gives us a new
appreciation for the courage and fortitude of our ancestors who
followed that route less than 200 years ago. Each stream and hill must
have presented a challenge, to say nothing of the larger rivers and
finally tall mountains that lay in their paths.
One of the moving moments of our trip
west occurred at the Garden of
the Gods, a public park donated to the city of Colorado Springs in 1909
by the estate of Charles Elliott Perkins. We rounded a corner among the
huge rock outcroppings and came upon a large group of teenagers sitting
together on the hillside. It was a high school choir from Florida on a
trip to Colorado and they were singing “Oh beautiful for spacious
skies...” a song written by Katharine Bates in 1895. She had traveled
by train from Massachusetts and was inspired by the World's Columbian
Exposition in Chicago, the "White City" with its promise of the future
contained within its alabaster buildings, the wheat fields of Kansas,
and the view of the Great Plains from Pikes Peak. We, too, felt the awe
she expressed in her poem as we traveled much same route. We live in a
beautiful country.
----------------------------------------
June
15, 2010: Strange Lights in the
Meadow
Mother nature has done it again – put
together another seemingly
impossible scenario that our scientists with all their expertise and
ingenious paraphernalia have not been able to duplicate – and it has to
do with a little bug that almost all of us as children collected on a
summer’s evening. A firefly is about ½ inch long, cigar-shaped,
and flies about in our yards, but what makes it exceptional is the
light it gives off, as even its eggs and larvae glow. There are about
136 different species around the world and they are common in the
eastern half of this country as well as in warm, humid areas around the
world.
Usually at dusk, the male firefly
emerges from hiding and flies about,
emitting one or a series of short flashes depending upon his species,
at regular intervals. The female waits on a low perch, and when a male
approaches, will give off an answering flash. Exchanges of signals are
repeated several times until the pair find each other and mate. Then
with luck the male will escape, as given the chance female will devour
him. After mating, the female will deposit her eggs in damp soil,
and in about three weeks young sowbug-like larvae will hatch with tiny
spots on their undersides that glow softly. All firefly larvae produce
light, possibly as a defensive measure, as it has been shown in the
laboratory that predators avoid such glowing objects after experiencing
their taste. The larvae are voracious predators that eat earthworms,
snails, slugs, and mites, injecting strong digestive juices into their
prey before sucking out the insides and leaving an empty skin. Most
firefly larvae live one to two years and are found in rotting wood or
other forest litter. In late spring they change into pupae, and in
about 10 days, emerge as new adult beetles that will live as long as it
takes to mate and produce eggs, often only a few days.
The last few segments of an adult
firefly’s abdomen are made up of
thousands of specialized cells that contain luceriferin and luciferase,
rare chemicals that generate light in the presence of oxygen, together
with an enzyme that provides energy for the process. The light emitted
by fireflies is unique in that nearly 100 percent of the energy is
given off as light. This is in contrast to tungsten electric lights
where only 10 percent of the energy is emitted as light and the other
90 percent is given off as heat. Although a few other insects can
produce light, fireflies are the only ones that can flash their lights
at will and it has only been recently that scientists have discovered
how it is accomplished.
Neurobiologists at Tufts University
were puzzled because they could
find no nerve link to the light-producing cells in the firefly’s tail,
although they did find that they could cause the cells to glow if they
exposed them to molecules of nitric oxide gas in the presence of
oxygen. Furthermore, they observed that the cells had a thick outer
layer of mitochondria, a substance that reacts with oxygen to create
energy for the cell and guessed that these mitochondria might be
blocking any light-creating chemical reaction. They also discovered
that a signal from the insect’s nervous system activated an enzyme that
produced nitric oxide that deactivated the mitochondria producing the
light. As the nitric oxide signal decayed, the mitochondria resumed
their oxygen consumption that turned the light off -- all of this
occurring in a fraction of a second. The fact that nitric oxide passes
through cell membranes, degrades within seconds and must be made fresh
for each use makes it an important transmitter and signaling molecule.
The really fascinating part of this
story is that scientists have found
that luciferin and luciferase are extremely useful as markers in
research on such problems as cancer, multiple sclerosis, cystic
fibrosis and heart disease. As all living cells already contain the
energy-providing enzyme, injection of the firefly's chemicals cause
flashes of light that can be measured and used to detect energy
problems in human cells. Now, electronic detectors, using firefly
chemicals, are used to signal that milk, food or water may be
contaminated with bacteria, and detectors have even been placed in
spacecrafts to look for earth-life forms in outer space. I read that if
as little as one quadrillionth of a gram of the enzyme enters the
rocket's detector, a flash of cold light will be given off and recorded
by earth-bound scientists.
Although most of the luminescent
species are insects, the capability is
also present in some bacteria, fungi, algae, one-celled animals,
segmented worms, arthropods and fishes. Some, like the fireflies, use
their light in courtship, while others use the flashes to frighten off
enemies or attract prey. The colors produced vary, as well, as some are
red, others blue-green or yellow. The problem is that not only are
luciferin and luciferase rare but they have proved difficult to
synthesize. This has made the propagation of fireflies a high priority
activity in some circles and the Sigma Chemical Co. of St. Louis,
Missouri purchases and provides fireflies throughout the world for
conducting research in a wide variety of scientific areas. I am told
that they will pay a penny for each bug if you will send them at least
25,000. Our bugs are completely safe from me, anyway...
June 8, 2010: One Bear, Two Bears,
Three Bears, More???
Bears are very much in the news these
days and I thought we might do
well to learn a bit more about them. North America has three or four
bear species, depending upon whether you count the grizzly and Alaskan
brown bear as variations on a theme or different species. The brown
bears live on Alaska's coastal range and nearby islands. Standing
erect, some males (boars) tower over eight feet, and on four feet,
stand as high as four and one-half feet at the shoulder. Most big males
weigh between 800 and 1,200 pounds with females averaging between 500
and 800 pounds. Grizzlies are somewhat smaller, standing three and
one-half feet at the shoulder and weighing up to 800 pounds. Once
widespread throughout much of western North America, grizzlies can now
mostly be found from inland Alaska across northern Canada to the Hudson
Bay, although a few remain in Montana and Yellowstone Park.
The polar bear is a huge, long-necked,
pear-shaped animal with thick,
whitish-yellow fur. Despite rumors to the contrary, a 2002 U.S.
Geological Survey of wildlife in the Arctic Refuge Coastal Plain noted
that the polar bear populations “may now be near historic highs” with
some 20,000 to 25,000 bears. Adult boars stand four feet at the
shoulder and are about eight feet in length and weigh about 1,000
pounds while females are typically smaller and lighter.
The black bear is the smallest of the
North American bears and is
thought to have arrived from Asia on the Bering Land Bridge about
500,000 years ago. Unlike the formidable grizzly, the shy black bear
has learned to adapt to man, and inhabits forests, swamps and mountains
from Alaska to the Gulf Coast. Though known to attack when provoked,
the black generally gives humans a wide berth.
Black bears mate in June and early
July and will breed with several
mates. During the 7 1/2 month gestation period, the fertilized eggs
float free in the sow’s uterus until late November when the egg
implants into the uterine wall and begins to develop. (This phenomenon
is called delayed implantation.) The cubs are born while their mother
is still in her winter sleep and are only 6 to 8 inches long, weighing
7 to 12 ounces. They develop rapidly and are able to leave the den in
late March with the female. The sow is a very attentive, protective
teacher, feeding her cubs and protecting them from other adult bears,
especially boars that would kill the cubs. Since it takes cubs 2 years
to become independent, sows do not breed every year and don’t chase her
cubs away when she again becomes pregnant. They will reach full size in
4 to 6 years.
Black bears locate their food by
relying on their keen sense of smell.
They feed mostly at twilight and through the night, and then spend the
daylight hours loafing in dense cover. They have large canine teeth,
but their molars are flattened for grinding and chewing tough plant
food rather than slicing through flesh, and plants make up a large
portion of their diet. They will eat just about anything, however:
fruits, berries, green leaves, tubers, acorns, nuts, ants, beetles,
bees, insect larvae, honey, fish, mice, squirrels, eggs, dead animals,
greasy grills, and garbage.
If food is scarce, bears will wander
and will be seen more frequently
during daylight hours. When they first emerge from their dens in
mid-March they are very hungry and because plants are still dormant at
this time of year, they must rely on small mammals and carrion for
food. As plants begin to sprout, bears switch to mostly green leaves.
With their powerful forelimbs and strong claws, they also rip open
rotten logs and anthills to feed on the insects, eggs, and larvae
hiding inside. They particularly enjoy tearing open beehives in trees
to feast on the stored honey.
In early summer the bears gorge on
wild strawberries and juneberries,
then on raspberries, gooseberries, blackberries, blueberries and
elderberries as each ripens, sometimes eating leaves, stems and all.
Later they switch to apples, wild grapes, acorns, and nuts – items that
that are high in fat and will help them put on the weight they need for
their long winter's sleep. Sometimes bears attack domestic livestock,
particularly lambs, piglets and calves. They will also raid beehives,
orchards, cornfields, and backyard birdfeeders, and can cause damage
when they rummage through garbage cans or demolish greasy grills left
out overnight. Healthy black bears can live 20 or 25 years, and hunting
is the primary method used to control their population from becoming
too large for society to tolerate.
Although some black bears can become a
nuisance, they are a very
important and beneficial part of Wisconsin's wild community. With
proper management, they will continue to provide thrilling subjects for
observation, photography and study. Report bear sightings to DNR
wildlife biologist Becky Roth, Spring Green, at 608-588-3432 or email
at Rebecca.roth@wisconsin.gov.
-------------------------------------
May 25, 2010: Robins, Brown
Thrashers, etc.
After months of waiting for spring,
suddenly it almost seems like
summer. The wooded hillsides are varying shades of green again, the
lawn grass needs to be mowed every few days, iris are blooming in
profusion, and not only do the male robins awaken us each morning with
their songs, but their first chicks are out of the nest and pleading
for food with never ending chirpings.
The American robin is a member of the
thrush family, all medium-sized
birds with rounded heads, longish pointed wings, and usually melodious
songs. It is named after the European robin because of the male's
bright orange-red breast, though the two species are not otherwise
similar. The female tends to be duller than the male, and the juvenile
is paler yet and has dark spots on its breast. During the breeding
season, male robins grow black feathers on their heads to attract
females but once the mating season is over, these feathers are lost.
While robins occasionally over winter
in the northern part of the
United States, most migrate south, departing in September and October
and returning north in February and March. The robin begins to breed
shortly after returning to its summer range and is one of the first
North American bird species to lay eggs. The nest is built by the
female and is commonly located in a dense bush or in a tree fork,
although she is very adaptable and will build in all sorts of
locations. She collects long coarse grass, twigs, paper, and feathers
held together with mud and moulds the nest into a cup shape with her
body and feet. She often then adds a final lining of soft grass, before
laying 3 or 4 “robin’s-egg-blue” eggs. It takes about 2 weeks to
incubate the eggs and the young stay in the nest for about 15
days. The female will begin a second clutch almost immediately
after they fledge, while the male continues to feed the first
youngsters another week or so.
The robin’s diet is mostly made of up
fruit and berries supplemented by
insects, larvae and worms. The reason we see so many robins searching
the lawns for worms is that these are the main food of the chicks in
the nest. At times, the robin will cock its head to the side toward the
ground and it was previously assumed to be listening for a worm. Now it
is understood that the bird is really watching for any tiny movement,
as its sight is much more acute than its hearing. When it does find a
worm, it often has to tug hard to pull it out of its hole. This is
because a worm's body has hair-like bristles called setae that help the
worm crawl and also to grip and anchor it firmly in the ground.
While many of our bird species are
declining, the robin is doing very
well and is thought to number about 320 million individuals. At one
point, the bird was even killed for its meat, but it is now protected
by the Migratory Bird Act. Its only problem is that it is a known
carrier for West Nile Virus. While crows & jays are often the first
noticed deaths in an area, the robin may be more responsible for the
transmission of the virus to humans. This is because while crows &
jays die quickly the robin survives longer, spreading it to more
mosquitoes that then transmit the virus to humans and other species.
The robin is not the only bird we are
watching these days, as a pair of
brown thrashers is also busy in the back yard. These birds are
robin-sized but are bright reddish-brown above with thin, dark streaks
on their buffy underparts and have long rufous tails. They like to feed
on the ground, poking long curved bills into the grass and ground
debris to find insects, seeds, and almost anything else edible they can
find. We assume the nest is in one of the thick shrubs back of the pond
but have been reluctant to look for it as the thrasher is notorious for
attacking any intruders and is quite capable of drawing blood with that
sharp beak.
The brown thrasher’s most interesting
characteristic is its song, as
researchers have been able to document some 3000 distinct phrases—many
of them mimicking the songs of other species or other sounds. The male
sings a series of short repeated melodious segments from an open perch,
each one repeated once. These repetitions also set the thrasher’s song
apart from those of its close relatives, the Northern mockingbird or
gray catbird, as mockingbirds repeat in groups of 3 or more while
catbirds do not repeat themselves at all.
The main enemy of both the robin and
brown thrasher is the housecat, as
the birds often nest in urban communities where the cats abound. In
rural areas, owls, hawks, crows, jays, snakes, squirrels, chipmunks and
raccoons also attack them, although most of these enemies feed on the
young or eggs, not the adult birds. Only 25% of the young survive the
first year and the average lifespan is only about 2 years. Populations
of brown thrashers are declining slowly across their range, perhaps
because of loss of habitat in the East and the elimination of fencerows
and shelterbelts across the Plains states.
We spend many contented moments
sitting on our porch watching the
various species of birds come to drink and bathe in our little pond.
Several types of finches, warblers, hummingbirds, flycatchers, jays,
bluebirds, red-wings, grackles, woodpeckers, tanagers, grosbeaks, and
mourning doves (and I’ve undoubtedly missed some), visit us regularly
and entertain us with their antics. We have great birding right at our
doorstep!
------------------------------------------
May 18, 2010: When is a Mouse not a
Mouse?
It must be tough being a mouse. Almost
every animal and bird in the
area wants to eat you, and should you find a warm and seemingly safe
house in which to live, the human resident sets a trap and tries to do
you in. Furthermore, there are a number of other related species vying
for all the available territories and food.
There are two general groups of
so-called mice in Wisconsin. One is
made up of jumping mice – mouse-like rodents that are distinguished by
their enlarged hind limbs, cheek pouches, and very long tails that are
used for balance while bounding. In Wisconsin these rodents can
sometimes be found in forest, pasture, cultivated fields or swamps.
They are nocturnal and generally live alone, and when disturbed, they
leap off with enormous bounds of eight or ten feet in length. The
female places her nest in clefts of rocks, under downed timber or in
hollow trees, and there are generally three litters in a season.
Members of the second group are called
murids and include true mice,
rats, and voles. These typically have slender three to four-inch bodies
plus scaly tails, and pointed snouts with prominent whiskers. Murids
generally have excellent senses of hearing and smell. The various
species may live almost anywhere and eat a wide range of foods with the
aid of powerful jaw muscles and gnawing incisors that grow throughout
life. Murids breed frequently, often producing large litters several
times per year. They typically give birth between 20 and 40 days after
mating, although this varies greatly between species. The young are
born blind, hairless, and helpless.
The house mouse is one of the most
numerous murid species and was
originally native to Asia—perhaps India. It spread to the Mediterranean
area about 8000 BC, across the rest of Europe by 1000 BC, and has since
been carried to all parts of the globe. It has been domesticated as a
pet and has been bred as a laboratory animal where it has proved to be
an important tool in biology and medicine.
The typical house mouse is 3 inches
long with another 3 inches of tail.
It is usually brown or gray and has short hair and a naked tail and
ears. House mice thrive in and around homes and commercial structures
as well as in open fields and agricultural lands. They consume and
contaminate food meant for humans, pets, livestock, or other animals
and often cause considerable damage to structures and property. They
also can transmit pathogens that cause diseases such as salmonellosis,
a form of food poisoning.
We are much more sympathetic with the
white-footed mouse, a native
species. It is about the same size as the house mouse but has white
underparts. This mouse can climb trees and uses its tail as a prop and
to help balance as it climbs. It is usually found in brushy fields and
woodlots and eats seeds, nuts, berries, fungi, and insects. It is adept
at food-hoarding and stores nuts and seeds during the winter months
when other food sources are scarce.
The deer mouse is very similar to the
white-footed but has a longer
multicolored tail. It also is a climber and likes to nest high in a
tree while the white-footed tends to stay closer to the ground. The
female deer mouse can breed at all times of the year, and so has the
highest reproduction rate among the murids. Deer mice feed on seeds,
fruits, spiders, leaves, and some fungi, and during the winter months,
invertebrate creatures compose about one-fifth of the deer mouse's
diet.
A third mouse, the Western harvest
mouse, is larger and can be found
from the Great Lakes to the Pacific Coast in grasslands, prairies,
meadows, and marshes. These mice average more than 5 inches in length
plus a 3-4 inch tail, and have large naked ears. They eat mostly seeds
but will also feed on green plants, grasshoppers and moths.
Voles are often confused with mice as
they look and behave much alike,
and are found in similar places. Still, they have several differences:
the vole has a stouter body, a shorter hairy tail, a slightly rounder
head, smaller ears and eyes, and differently formed teeth.
What we often call the field mouse is
really a meadow vole, and in
Wisconsin, there are also red-backed and prairie voles. Voles often
live in open fields as opposed to wooded areas, and are abundant
wherever there are lots of plant cover. In winter, they tend to remain
below the snow surface in tunnels, and in the spring they move around
in surface tunnels through the vegetation. Voles eat mainly grass but
may gnaw on tree bark and will eat nuts and seeds when available.
Whether mouse or vole, these little creatures are very important parts
of the natural world and form vital links in the chain of life.
---------------------------------------------
May 11, 2010: The Weasel: A
Killing Machine
With the exception of deer, squirrels,
and rabbits, we seldom see even
the most common wild animals that live here on the farm and around the
area. Coyotes, skunks, foxes, opossums, chipmunks, woodchucks,
raccoons, and mice carry on their lives all around us, but most are
active during the nighttime hours and in relative secrecy. One
reportedly abundant animal that we have only seen once or twice in the
35 years we have owned this property is the weasel.
The weasel has an undeserved bad name
in society – almost as bad as
that of the skunk – but its actions and not its smell are the basis for
that prejudice. Its name is often applied to a person who achieved
something by cunning or deception; the animal, itself, on the other
hand, just does what it must to survive, as it is driven by an extra
high metabolism that requires it to eat almost constantly.
The mustelid family in Wisconsin
contains a number of species – otters,
badgers, minks, declining numbers of wolverines, martens, and fishers,
and two weasels. These weasels are differentiated by size and tails,
and are called the long-tailed and least weasels.
The long-tailed weasel lives in all
types of habitat from southern
Canada to Central America and is thought to be the most widespread
carnivore in the Western Hemisphere. Two of its favorite prey species
are mice and voles but it also feeds upon rabbits, chipmunks, shrews,
birds, rats, and chickens. Weasels are known to be good climbers and
excellent swimmers, and are notorious (fact or fiction?) for killing
entire coops of chickens. They kill with a few quick bites to the base
of the skull.
The long-tailed weasel has an
elongated slender body with a long neck
and short legs. It molts its short, soft fur twice each year in
response to changing day length. The spring molt in March results
in a brown back and sides with white chin, neck and belly and a brown
tail with a black tip. The fall molt in October or November
results in an all white coat with a black-tipped tail.
It has an unusual breeding cycle, as
the male searches out a receptive
female early in the summer. After fertilization, the ova develop for
about 68 days before coming to a halt. Implantation in the uterus
doesn’t take place until early in the next spring, after which
development continues for three to four weeks. A litter of four to five
blind and mostly naked pups is then born in April or May. They grow
quickly and by the third week, the young have their adult fur and their
first set of teeth. In week five, their eyes open and they are
weaned. By their fourth month they have their adult teeth and
have reached adult weight. Females often mate late their first summer,
while males do not reach sexual maturity until their second summer when
they are about 15 months old.
Male long-tailed weasels are about
13-16 inches long (including the
tail) and weigh almost a pound while females are about three inches
shorter and up to 6 ounces lighter. The least weasel is quite similar
in many ways but is much smaller, with a male averaging only 8 inches
in length and weighing an ounce and a half, and a female only seven
inches long and weighing little more than an ounce. Its tail is never
longer than 4 inches and lacks the black tip.
Male least weasels reach sexual
maturity at eight months, while females
are able to breed at four months. Females may have two litters a year,
and have a gestation period of less than five weeks in contrast to the
long-tailed weasel’s delayed implantation. Despite their small size,
the least weasels are vigorous killing machines. Small rodents make up
the majority of their diet, and each must consume half of its body
weight every day to survive (about two deer mice or one meadow vole
each day). Both male and female least weasels have body diameters no
larger than their prey, which allows them to follow rodents into
burrows, tunnels, and matted grass. They often then take over the den
for their own use.
The weasel is active year-round,
hunting, feeding, and sleeping during
the day as well as night. It will cover an area of two acres while
searching for prey, and commonly will have more than one den. When it
can, a weasel will kill more than it can eat and store any excess in
its den for future meals. The long-tailed and least weasels probably
live for only a couple of years and most die before reaching adulthood.
Still, they are important in the nature’s plan and of help in many
human endeavors because of the large number of rodents they consume.
------------------------------------------------------
May 4, 2010: Garlic Mustard: Wanted: Dead and Not Alive!
After weeks of enjoying the emergence of one wildflower after another,
we have switched our attention to a couple of plant invaders that may
threaten their existence. Wind, water, wildlife and humans disperse the
seeds of these problem plants, which compete with and are capable of
overwhelming our native species. Some are commonly sold landscape
plants such as barberry, burning bush, shrub honeysuckle, multiflora
rose and oriental bittersweet, while others were introduced either
intentionally or accidentally as medicinals or agricultural crops such
as garlic mustard, buckthorn, and reed canary grass.
Our current focus here at the farm is upon the garlic mustard that is
entering our woodlands across our north and east fence lines. This is a
rapidly spreading woodland weed that can dominate the forest floor and
displace most native plants in just a few years. Unlike other plants
that invade disturbed habitats, garlic mustard readily spreads into
high quality forests and is a major threat to the survival of
Wisconsin's woodland plants and the animals that depend on them. It is
a cool season biennial herb with stalked, triangular coarsely toothed
leaves that give off an odor of garlic when crushed.
First-year plants appear as a rosette of leaves close to the ground
that remain green through the winter and develop into flowering plants
the following spring. Viable seeds are produced a short time later, and
by late June, they can be recognized only by the erect stalks of dry,
pale brown seedpods that remain through the summer. This plague
was introduced from Europe in the 1800s, presumably by early settlers
for its supposed medicinal properties and for use in cooking, and is
now widely distributed throughout the northeastern and Midwestern U.S.
from Canada to South Carolina, and as far west as Colorado and Utah.
It is in full bloom in April and May and easy to identify as its
clusters of small white flowers on upright stalks are unique at this
time of year. We are told that not only must these plants be pulled,
but also they must be bagged and carried off as seeds are reported to
continue to develop. We had never seen this species here at the farm
until a few years ago but now they have appeared in discouraging
numbers and a pile of packed garbage bags awaits pickup at the road
each week.
At this point we are overwhelmed with eradicating garlic mustard, but
we also notice all the alien barberries that are sprouting up
everywhere, as well. These are compact, spiny shrubs that usually grow
from two to three feet tall and have been widely planted as clipped
hedges around urban yards. They have attractive bright-red berries that
mature in mid-summer and hang on for several months, and their leaves
turn lovely shades of red and yellow in autumn. The problem is they are
eaten by many species of birds that then spread their seeds across the
landscape. The only plus about the barberry is that it is vulnerable
for months instead of a week or so, and therefore we can hold off our
attack on its populations until we have dealt with other problems.
Another major invasive we fight is the Canada thistle, a misnamed plant
since it was also brought to this continent from Europe. Unlike most of
the other nuisance plants, its potential for trouble was recognized
almost immediately as it caused difficulties even in its native habitat
where natural enemies were present. Canada thistle has a deep and
wide-spreading root system so that dense patches can be formed from a
single plant. Small fragments of the roots can sprout new plants, so
cultivation only spreads the plants into new areas. In addition, an
individual plant can produce up to 1500 seeds and about 90% of the
seeds will germinate within one year. Some can remain viable for up to
20 years. To be certain that its seeds are dispersed, the plant
provides them with parachutes that can be blown a half-mile in the
wind. Pulling such a plant is ineffective and we cut and treat each
stalk with chemical herbicide.
Landowners with wetlands can have several other species attacking their
properties. Purple loosestrife was introduced to North America in the
early 1800's from Eurasia and it has found its way into wetlands in
nearly every province and state in North America. It is a very hardy
perennial plant with a dense mat of roots that can out-compete
cattails, sedges, rushes and the other native aquatic plants on which
wildlife depends. Reed canary grass is also increasingly dominating wet
meadows as it is a prolific seed producer and spreads through rhizome
growth at an amazing rate.
Then, should you have escaped all of the above, there is buckthorn
(from which we are thankfully free), honeysuckle, multiflora rose, etc.
etc. etc. With all these immigrants, I wonder if we will ever be able
to just sit back and enjoy the scenery.
-----------------------------------------------------
April 27, 2010
Are you familiar with the shinleaf,
mayflower, blue cohosh, rue
anemone, lousewort, or spiderwort? All are quite common wildflowers in
our woodlands and prairies, but we often overlook them for the more
showy trillium, wild geranium or butterfly weed. Look for them as you
walk in wild areas these early spring days.
Shinleaf is the rather unattractive
name for a lovely little plant. It
was once thought to be a cure for rheumatism and the leaves of this and
other members of its family were used as plasters for bruised shins and
other sores and wounds, hence the name. It is also called wild
lily-of-the-valley, but I much prefer the scientific name of pyrola,
rather than borrowing one from a garden flower. The leathery
rounded leaves of pyrola persist through the winter, and in the spring
each basal rosette puts up a 6” upright flower stalk. It does resemble
a lily-of-the-valley, as it has nodding waxy-white flowers that hang
from the upper part of each stalk. It is very fragrant and even though
the individual flowers are small, it often grows into colonies of some
size and the combined scent can often be detected before any flowers
are discovered.
Canada mayflower is another small gem
of the woodland that covers large
areas when conditions are favorable. A young plant, either from seed or
from a spreading rhizome, consists of a single shiny heart-shaped leaf
at first, but as it matures it puts up a small stem that supports two
alternately placed leaves with flowers at the top. (Some even call it
two-leaved Solomon's plume.) The tiny half dozen or so white flowers
are replaced by greenish speckled berries that later turn pale red. Few
of the berries mature, however, as they are a favorite food of grouse.
Blue cohosh was named by the Native
Americans who brewed a bitter tea
from its roots for medicinal purposes. It likes to grow in rich
soil, and has become a sort of litmus test for the health and wealth of
a wild area. Its finely divided bluish-green foliage unfolds in threes
on the top of stiff stems, and then is divided again into three
additional divisions consisting of three leaflets. In May and June it
puts out a bouquet of small yellowish green flowers that later develop
into blue berry-like seeds about the size of large peas.
The rue anemone has a somewhat similar
lobed leaf, but is much smaller
and more delicate. It grows profusely throughout our woods and opens
its white or pink flowers over an extended period, in contrast to many
of the other early plants. The wood anemone often blooms nearby with a
similar white blossom but can be easily distinguished because it has
but a single bloom to each stalk.
Lousewort is a “lousy” name for such a
interesting looking plant. The
leaves are fairly easy to identify as they are long and narrow with
deeply-cut teeth, and grow in a tightly-packed whorl in sunny open
patches. The early leaves are hairy and usually a deep purple color,
but soon turn green as a round head emerges. The individual yellowish
flowers bloom in a spiral around the outside of the flower head and
appear hooded at the top, much like a mint, but it is actually related
to mullein, turtlehead, and beardtongues. Incidentally, another name
for this plant is wood betony, a term I much prefer.
While the lousewort name came from the
old world belief that livestock
that grazed on this plant would get lice, (they probably did, though
not due to anything they ate), spiderwort was presumably named because
the plant vaguely resembles a large spider when viewed from above. This
oddly shaped wildflower is a monocot, one of those plants whose leaf
veins run parallel to the edges as do lilies, iris, and orchids, rather
than branching from a centerline. Its lavender, three-petalled flowers
are found in clusters at the top of the stems among numerous buds that
open over many days, and its stiff leaves are long and narrow.
You can see all of these and many more
wildflowers if you attend our
open house this weekend. The early warm temperatures have brought many
of the plants into bloom, so come and stroll through the wild garden,
hike any of the trails, and purchase any plants that you’d like to take
home with you. Hope for nice weather!
------------------------------------------------------
April 20, 2010: Blues, Coppers, and More...
It is a mystery what interest a
butterfly might have in our gravel
driveway, but on a sunny April day after a rain, we often find several
probing their tube-like proboscises down between the stones. Some of
the first visitors each spring are so tiny they might be stepped upon,
except they don’t allow anyone to get that close before flying off.
Many of these are belong to the
gossamer-wing family – butterflies that
get their common names from their appearance. Some groups have shiny
blue on their wings, while others are the color of copper. Some have
very thin little "tails" on their wings and are called hairstreaks.
Others are not so colorful, and have gray or brown wings with spots of
black, white, or orange. They are usually very small, with wingspans of
less than an inch. The males of a few of the species have reduced front
legs like the Brushfoot family, but all the females have 6 legs for
walking and standing.
There are nearly 5,000 species in this
family around the world, but
most live in the tropics. We only have about 145 in the United States,
and 32 species in Wisconsin. I find an individual almost impossible to
identify without catching it with my camera and then sitting down with
my trusty Peterson’s Field Guide to Butterflies, as the differences
between the various species are often slight and difficult to see. I
think the ones that have been fluttering around on the drive this week
are spring azures, but I am usually content to use a subfamily name –
hairstreak, harvester, blue, or copper – all of which can be seen in
Wisconsin at one time or another.
Probably, the most widely known is the
Karner blue, because it has been
placed on the federal endangered species list and given quite a bit of
publicity. The situation is brighter in Wisconsin, however, as
there are spots where it seems to be holding its own, so that here it
is considered only “a species of concern”. The Karner blue’s problem is
that its larvae feed only on one plant – the wild lupine. This was once
an abundant wildflower, but many of the oak savannas and pine barrens
where it flourished have been changed by development, agriculture,
roadside management, and conversion into shrubby woodland.
The Karner blue has two hatches each
year. The summer females lay their
eggs on low plants on or near the ground near lupine plants where they
remain until the following spring. In April, miniscule caterpillars
hatch and feed on the leaves of the sprouting lupine. In mid-May, these
caterpillars pupate and adult butterflies emerge out of their chrysalis
around late May or early June. The adults will feed on the nectar of a
variety of flowering plants, mate and then lay their eggs on the lupine
plants. The eggs will hatch in about a week to feed on the lupine
leaves for the next three weeks and then become the adults that will
produce the eggs for next year’s butterflies.
The caterpillars of all the
gossamer-wing butterflies have small heads
and legs, and sometimes look like green or brown slugs covered with
tiny hairs. Some can even pull in their heads completely, like a slug.
An interesting fact about many of these caterpillars is that they have
a cooperative relationship with certain ants. Each has a gland that
excretes a sugary substance that is a high-energy food source which
ants seem to crave. In some cases the caterpillars secrete drops of
this honeydew when the ants tap them with their antennae (an action
some have dubbed “milking”. It is reported that the ants have even been
observed to herd the caterpillars, leading them to feeding areas in the
daytime, and bringing them inside the ants' nest at night.
The harvester is another fascinating
creature as it is the only
butterfly whose caterpillar is carnivorous – that is it eats aphids and
scale insects rather than leaves. This butterfly has black spots and
orange-brown areas surrounded by black while the underside is
orange-brown with faint white circles. The females often lay
their eggs in colonies of woolly aphids but the caterpillars themselves
are often preyed upon by ants and usually spin a silken covering over
themselves for protection. The adult has a short proboscis suited for
feeding on aphid honeydew as it does not sip flower nectar.
Butterflies are often called “flying
flowers” and let me remind you
that this Saturday and Sunday you are invited to attend the Timbergreen
Farm wildflower open houses. There will be potted and growing prairie
and woodland wildflowers available and lots of flowers (and
gossamer-wing butterflies unless the predicted rain materializes) to
enjoy. We will be here rain or shine and happy to greet you.
--------------------------------------------------------
April 13, 2010: Look at all the
Bloomin' Trees!
Viewing the flowering trees is one of
the many delights of springtime
and we watch for the apple, pear and plum blossoms to appear. Many of
us may not realize, however, that all of our lawn and forest trees also
bloom, for they could not produce seeds without flowers. Some of these
blossoms have strange shapes and others must be examined with a
magnifying glass to be really appreciated, but almost all are colorful
and beautiful in their fashion. Most trees are wind-pollinated and
after discharging their pollen, the flowers wither and soon disappear.
Others, however, last longer and are pollinated by insects, and these
almost all have showy, attractive flowers that are often fragrant and
full of nectar.
Trees have a variety of stratagems for
accomplishing their sex lives.
Some produce blossoms that contain both male and female organs – so
called perfect flowers. Some have their male and female parts in
separate blossoms on the same plant. There are also species that
not only have "perfect" flowers, but also either male or female flowers
or both. Then there are those where the entire plant is either male or
female.
Of the “perfect flower” trees, elms
and maples are probably most
common. The American elm has tiny red flowers but they are so small and
delicately tinted that they are seldom noticed. Each has both stamens
that shed pollen and a pistil that receives it to fertilize an egg that
will develop into a seed.
Maple trees have inconspicuous
clusters of green, yellow or red flowers
at the end of their young shoots but in good years, there are so many
that the entire tree appears as though enveloped in a colorful haze.
The flowers of sugar maple are greenish yellow with long stalks hanging
in drooping clusters and appear with the leaves, while in the Norway
maple the flowers are yellow to chartreuse. The red maple has – you
guessed it -- red flowers and the buds that appear before the leaves
emerge are also a deep scarlet. These flowers stand upright, unlike
other tree flowers, which generally hang down. The pollen spreads from
flower to flower and some of the clusters of flowers are even able to
pollinate themselves. Most pollen is carried by the wind, but flies and
other insects often help.
Oaks, as well as many other forest
trees have peculiar flowers in the
form of catkins that do not look like flowers at all as they have no
petals or sepals. The catkins somewhat resemble dangling yellow worms
and are made up of clusters of flowers that contain only
pollen-producing stamens. The female flowers consist of reddish 3-lobed
stigmas above egg-shaped organs that will later develop into acorns.
Oaks have male flowers on one part of a branch, and female flowers on
another part of the same branch. Black and red oaks require two years
for this process while white and bur oaks need only one.
Walnuts, hickories and birch
also have slender catkins of
inconspicuous, green male flowers hanging from their twigs while short,
even less noticeable female flowers grow at the branch tips on the same
trees. Willows, cottonwood and other poplars, box elder, mulberry,
Osage orange and sassafras produce their male and female flowers on
separate trees, and of course, only the female trees produce seed.
The catalpa or catawba tree has the
showiest flowers in the forest and
actually belongs to the trumpet vine family. It can be recognized by
its large heart-shaped leaves, showy white and yellow flowers, and in
the autumn by its long fruits that resemble long bean pods. It is
native to warm temperate regions of North America, the Caribbean, and
East Asia and has been widely planted outside their natural ranges
because of their attractive flowers and pleasing shape. We have several
in the woods here at the farm and they can be seen throughout our
region.
No flowering tree is more beloved than
the apple, however. It seems to
have originated in eastern Turkey and was perhaps the earliest tree to
be cultivated. Apples were brought to North America with colonists in
the 1600s, and the first apple orchard on the North American continent
was said to be near Boston in 1625. Its blossoms have been lauded in
song and folklore and many are planted solely for their flowers and
their fruits discarded.
As you look to the trees, take time to
examine what is under them, as
well. The ground is coming alive right before our eyes as one species
after another of wildflowers makes its appearance. Then mark your
calendar to drive out to the farm during our openhouses – the last
weekend of April or the first weekend of May. There are trails to walk,
prairie and woodland wildflowers to view and purchase if you wish, and
lots of good talk with other enthusiasts of the wild world. We hope to
see you.
--------------------------------------------------
April 6, 2010
So what is going on at the farm this
beautiful April day?
The robins greeted the dawn—first
singing from chosen perches, then
checking the lawn for worms and insects.
The tree tops in the woods across the
field have taken on lovely pale
pink and yellow hues as their flowers begin to bud and then open. The
grass has also begun to green up again after months of browns and tans.
An azure bluebird and his mate are
checking out the new house Bill put
up for their use just last week, and we hope they will remain to raise
a family or two in it.
Several song sparrows are singing from
various spots around the
farmyard. They, too, are staking out territories in a most pleasant way
and entertaining us in the process. They are regular visitors to the
waterfall above the little pond in our back yard, splashing away with
obvious enjoyment.
Daffodils, crocus, scilla and
Johnny-jump-ups brighten the bare earth
of the gardens, and my collection of Lenten roses is showing promise of
becoming a favorite spot as each young plant matures sufficiently to
send out blooms.
The phoebes arrived last Wednesday,
and announced their presence by
calling their names over and over. They are the flycatchers that always
nest over the door of the little stone building that we use as a shop
during our wildflower sales.
More flowers open in the wild garden
each day—hepaticas, spring
beauties, bloodroot and Dutchman’s britches—and it is like a treasure
hunt to discover each new species as it appears.
Redwing blackbirds have perched on
every available weed stalk in the
old field below the house, calling their “o-ka-leeeee”. They have
experienced much competition as such stalks are few and far between
this year due to the heavy snow that flattened almost all.
The vultures have returned and circle
above the rock point that rises
high above the farmyard. We are convinced they nest up there somewhere
but have not been able to find their sites.
Also overhead, sandhill cranes and
Canada geese fly, some of them
passing through on their way North and others scouting the territory
with plans to settle in and set up housekeeping.
The barred owl pair keeps in touch
with hooting and calling in the draw
above the wood kilns. They undoubtedly have chicks tucked into a hole
in one of the old trees on the hillside.
The eagles that nest down on the
country highway along the marsh must
be brooding eggs by now and soon will be scouring the countryside for
food for ravenous babies.
Amorous tom turkeys, now triple their
usual size as they display their
finery, gather around any hens that venture out into the fields to feed.
Several species of butterflies visit
the damp spots in the drive. The
mourning cloaks with their maroon wings edged with cream and the
painted ladies with their orange and black wings have spent the winter
hidden in sheltered spots around the farm buildings and emerge long
before it seems reasonable for such fragile creatures. They feed on
tree sap and nectar from any flowers that are open, including those of
maples and aspens.
Welcome rain arrives with sometimes
spectacular lightning and thunder,
a major change from winter’s usually quiet snowfall.
The ground is speckled with small
holes, each surrounded with a ridge
of dirt where earthworms have partially emerged looking for mates and
then quickly returned to their underground lives.
The spring peepers serenade us each
warmish evening, making far more
noise than seems possible considering their small size. Soon their
tadpoles will appear in both ponds, along with those of the green frogs
that survived the winter. The toads will join them and the water will
seem alive with their nuptial activities before too many days.
Whippoorwills call, sometimes several
at a time, but although we
understand they are still common in other areas, they seldom come to
serenade us at the farm as in years past.
Woodcocks perform their unlikely
courtships, climbing high into the sky
and then dropping to parade before their prospective mates.
The dawn arrives earlier and sunset
comes later as the season
progresses, and we blossom, along with the wildlife, in the sun and
mild temperatures. Spring is a glorious time of the year and we live in
an area few others can equal.
---------------------------------------
March 30, 2010
The first flowers to appear in our
gardens are all introductions from
Europe and Asia that don’t know that the middle of March can still be
quite winter-like in Wisconsin. Our native plants understand that it is
risky to push the season, but crocuses, daffodils and snowdrops are
amazingly hardy and usually survive the almost certain freezes and even
snow storms that often continue to plague us even into April.
Crocuses are native to central and
southern Europe, North Africa and
the Middle East, across Central Asia to western China. Daffodils come
from the Mediterranean region, in particular to the Iberian Peninsula,
as well as Northern Africa and the Middle East. Snowdrops can be
found across a large area of Europe, stretching from the Pyrenees in
the west, through France and Germany to Poland in the north, Italy,
Northern Greece and European Turkey.
Some of our native plants here in the
southwestern hills of Wisconsin
do appear in late March—the first almost always being the hepatica.
(Skunk cabbage is often earlier but can only be found in the wet
marshes). I read that hepatica may grow in a wide range of conditions
from deeply shaded deciduous woodland and scrub to sunny grassland,
although I have never seen it growing in the sun. Our plants thrive in
the rich soil on the wooded hillsides and each year we marvel at how
they have spread.
Hepatica received its name from its
leaves, which, like the human
liver, have three lobes (the Greek word for liver is hepar). Before the
advent of modern medicine, humans found that some plants seemed to help
a variety of maladies and diseases. Such connections were probably
first recognized in ancient China, where they correlated plant features
to human organs. Yang (primitive male) was associated with strongly
acting plants and ailments of the upper half of the body were treated
with upper parts of plants. Yin (primitive female) was associated with
plants having moderate action and those with bitter, sour, salty, and
sweet tastes and ailments of lower parts of the body were treated with
below-ground plant parts. Furthermore, yellow and sweet were
associated with the spleen, red and bitter with the heart, green and
sour with the liver, and black and salty with the lungs.
In Western cultures, the use of plants
for medical purposes emerged
during the Middle Ages, when people believed that human destiny was
determined by the stars and everything upon the earth was created for
the sake of mankind. Some religious people believed that plants were
placed on earth for the good of mankind and God must have provided
visual cues to their use. They theorized that the key must have been
hidden in the form (signature) of the plant itself, and so the Doctrine
of Signatures was developed. The most famous advocate of signature
plants was Philippus Aureolus von Hohenheim. This Swiss citizen later
adopted the Latin name Paracelsus and during the first half of the 16th
century, he traveled throughout Europe and to Asia and Egypt, treating
people with his concoctions.
The Doctrine of Signatures was highly
popular during the Renaissance,
and many plant names indicate how plants were once used—some of them
highly imaginative. In general, long-lived plants were used to lengthen
a person’s life, and plants with rough stems and leaves were believed
to heal skin diseases. Plants with yellow sap were cures for jaundice,
and roots with jointed appearance were an antidote for scorpion bites
and flowers shaped like a butterfly became cures for insect bites. Thus
we have plants named liverwort, snakeroot, lungwort, and maidenhair
(supposedly a cure for baldness!). Although hepatica is no longer
popular as an herbal remedy, it does act as a mild astringent and
diuretic and has limited success as a laxative. However, not too long
ago, it was viewed as the cure-all for most ailments including
freckles, indigestion, and cowardice.
Hepatica reaches a height of 4 inches
and produces lovely flowers. The
leaves rise on short stalks and are dark leathery green, each with
three lobes. The flowers may be white, bluish purple or pink and appear
singly on hairy, leafless stems, and are pollinated by butterflies,
moths, bees, flies and beetles. In autumn, the leaves turn shades of
russet and purple and persist through winter. It is critical that the
leaves remain during the winter months, as the plant continues to use
them as a source of nourishment.
As soon as the snow melts, one can
often find buds pushing up through
the debris from the crowns of old leaves and several sunny days will
encourage them to open their fragile blossoms. If you don’t have any in
your garden, you should find a spot for these treasures.
-------------------------------------------------------
March 23, 2010: Well I swan!
Most bird watchers are aware of the
dedicated group that has been
working to reintroduce the whooping crane to Wisconsin and the Midwest.
Its spectacular efforts have included the rearing of a group of new
chicks in seclusion each summer and then leading them by ultralite
planes to Florida in the late fall. As of early February 2010 there are
now thought to be 85 wild birds in the Eastern Migratory Whooping Crane
population, consisting of 48 males and 37 females. The most recent
known locations of all birds are 26 birds in Florida, 3 in Georgia, 4
in South Carolina, 6 in Alabama, 1 in Mississippi, 15 in Tennessee, 8
in Kentucky, 8 in Indiana, and 7 at undetermined locations.
This is not the only restoration
endeavor, however, as another group is
working to reintroduce the trumpeter swan, the largest waterfowl
species in North America. These birds were present in Wisconsin until
the 1880s but they disappeared due to market hunting and feather
collecting. Efforts to restore them have been dramatic, with the number
of breeding pairs increasing nearly 100 percent over the last five
years, according to Sumner Matteson, a DNR avian ecologist who
participated in the recovery program.
The adult trumpeter swan has all white
plumage, a black bill with a
narrow, salmon-red stripe along the base of the lower bill, and a
wingspan of nearly 8 feet. Juveniles are sooty gray with black-tipped,
pink bills. They do not become all white with a black bill until about
a year old. Individuals can live to 20-30 years of age and most weigh
21-30 pounds, although large males may exceed 35 pounds. Trumpeters
have broad, flat bills with fine tooth-like notches along the edges.
This helps them strain aquatic plants from the water as they feed. The
birds' long necks and strong feet allow them to uproot plants in water
up to 4 feet deep.
Trumpeter Swans arrive in their
wetland breeding grounds soon after ice
melt in early spring and normally choose a spot near where the female
(called a pen) was hatched. The pair, that bonds for life, builds a
6-ft diameter nest in mid-April atop a muskrat or beaver lodge or on a
mound of vegetation and lays 5-9 off-white eggs. The pen incubates the
4½-inch eggs for about 33 days while the male (called a cob)
defends the nest. The cygnets fly at about 14 weeks and in autumn join
the other swans in migrating to areas with ice-free streams and ponds
in Illinois, Indiana, Iowa, Missouri, and Oklahoma.
Under a 1986 trumpeter swan recovery
plan, Wisconsin biologists working
with Mary and Terry Kohler of the Windway Capital Corporation flew to
Alaska for nine consecutive years beginning in 1989 to obtain swan
eggs. Each year they collected about 50 surplus eggs that were then
hatched in incubators at the Milwaukee County Zoo. The cygnets were
either placed in a captive-rearing program or decoy-rearing program
until they were released to the wild. The original recovery goal was to
establish a breeding and migratory population of at least 20 pairs by
the year 2000.
In 2009, biologists counted a record
183 trumpeter swan nests in 23
counties. Despite relatively poor nest success this past year, due
primarily to drought conditions in northwestern Wisconsin where the
largest percentage of nests are located, a total of 317 young swans
fledged from nests in Wisconsin last summer, Matteson says. The problem
is that many of the young cygnets don’t have parents to show where to
migrate and not all of them end up in the best of winter homes.
Now The Trumpeter Swan Society (TTSS),
Arkansas Game & Fish
Commission, The U.S. Fish and Wildlife Service and others have teamed
up to help the young swans to find good winter habitat. Nine-month old
free-flying trumpeters have been captured from ponds of private Iowa
swan propagators and released in two sites in Arkansas—The National
Park Service's Buffalo River and the Holla Bend National Wildlife
Refuge—where they will find the food, water and protection from
predators. Hoffman says many young swans were wandering into marginal
habitat during migration, and reducing their overall chances for
survival. Wildlife biologists hope the swans’ new winter homes will
click in their migration memory next year, when it is time to migrate
again.
Perhaps it was one of these swans that
was spotted along a road near
here last week. It was a juvenile as could be told by its “sooty” neck
and was somewhat of a worry because it stayed in the wet field for two
days. On the third it went on its way, however, and hopefully joined a
passing flock. Should you see any of these magnificent birds, you might
want to look for a neckband and report its presence. You will be part
of an on-going effort to repopulate our state with one of its more
spectacular native species.
-------------------------------------------------------
March 12, 2010: Birds on the Move
Last week on a warmish foggy evening,
I was reading in my living room
when something or someone scraped at the window behind my chair. I was
startled and peered out into the darkness but could see nothing. In a
minute or so the sound came again, and this time I saw a small form
flutter against the glass before disappearing again. What was a bird
doing at my window at 10:00 PM?
The fact is, although we think of most
small birds as creatures of the
daylight hours, during migration they travel at night. I am guessing
that this one became separated from its companions in the fog and while
trying to find its way, was attracted to my light. Birders around the
state are reporting that robins, killdeer, waterfowl, red-winged
blackbirds, grackles, song sparrows, sandhill cranes and other early
migrants have arrived or are passing through, and we have seen or heard
most of these here at the farm this week.
Most birds outside of the tropics
migrate for one of two reasons: they
must move to an area with a more plentiful food supply when the weather
becomes inclement, or they migrate to a specific area to breed and
raise their young. Up to 80% of the birds that breed in North America
migrate south for the winter. Some can survive on seeds and fruits even
though they eat insects much of the year, and travel only as far as
they need to go to find food. They are the first to return to
Wisconsin, beginning in March. Long distance migrants migrate to
Mexico, Central and South America and the Caribbean, and these birds
actually spend more time in the tropics than on their North American
breeding grounds. They eat mainly insects and do not arrive until April
and May when these are plentiful.
To give you an idea of the magnitude
of this phenomenon, radar studies
indicate that at the peak of migration, more than 30 million birds
cross the Illinois-Wisconsin border each hour. (This amazing number
comes from the National Center for Atmospheric Research and is obtained
from NEXRAD images). Some geese and ducks fly at incredible heights.
Bar-headed geese have been recorded as high as 29,000 ft when they
migrate over the Himalayas. However, most night-migrating songbirds fly
below 2,000 ft. when flying over land although they may fly higher to
take advantage of favorable winds. In still air, most songbirds fly at
20-30 mph while waterfowl and shorebirds can fly at 30-50 mph.
Tailwinds can increase their speed considerably.
A bird may use the sun, the stars
and/or the Earth’s magnetic field to
find its way. Many day fliers use the position of the sun during the
day to navigate. Night flyers find their way by learning the patterns
of the stars in the sky, and by knowing special stars like the North
Star. Hard as it may be to believe, experiments have shown that birds
memorize the position of the constellations in relation to the North
Star in their first year of life. Scientists have also discovered that
birds have tiny grains of a mineral called magnetite just above their
nostrils, and it is postulated that this mineral may help them to
navigate using the Earth’s magnetic field, which indicates to the bird
the direction of magnetic north.
Many soaring birds, such as hawks,
migrate by day. They save energy by
using columns of warm air called thermals that spiral upwards and lift
birds up without flapping. Insectivores, such as swifts and swallows,
also fly during the day, feeding on insects as they fly. On the other
hand, most songbirds travel during the night. Many take off about 30
minutes after sunset and the rest in the next several hours. They spend
the daylight hours resting and searching for food in the unfamiliar
places where they stop to rest.
Night-migrating birds that navigate
primarily by the stars sometimes
become disoriented by city lights. They seem to confuse lights in tall
city buildings with starlight--especially in foggy or rainy weather,
and particularly after midnight, when the birds begin to descend from
their peak migration altitude. Once disoriented, many birds collide
with the buildings and fall to the sidewalks below. Others, like moths
attracted to light, flutter around the lighted windows until they are
exhausted. Birds by the hundreds and even thousands can be injured or
killed in a single night at just one building.
To find a solution to the night-lights
problem in his city, Toronto
artist Michael Mesure founded an organization called the Fatal Light
Awareness Project (FLAP) in 1993. FLAP asks all cities to extinguish
all interior building lights and non-essential floods and other outdoor
lights, and to shield essential lighting during migration time. The
Toronto skyline is now darker because over 80 buildings have agreed to
participate in the "Bird-Friendly Building Program." The November 2000
issue of Architecture Magazine reported that Chicago's Hancock Center
has also doused its ornamental nighttime lighting, thereby saving many
of the nearly 1,500 birds that formerly died each night when they
crashed into the tower during the migration season. The satellite view
of the country at night showing how much is brightly lit is a sobering
sight and anything we can do to reduce the problem is all to the good.
-------------------------------------------------------------
March 10, 2010: House Sparrows and
Spring
There are varied signs of spring:
warmer temperatures with disappearing
snow banks, geese and cranes flying overhead, cardinals and titmice
singing, and even the distinctive smell of an angry skunk wafting down
the valley. Still there is another sign that is just as predictable but
which often goes unnoticed.
Husband Bill and I were sitting at our
kitchen table eating breakfast
when my attention was caught by a flurry of feathers on the porch
outside. Two house sparrows were rolling and tumbling on the
deck—first one on top, then the other. They were scratching at each
other’s bodies with their outstretched claws, while each had a
beak-full of whatever body part it could clamp onto. Wings flapped
against the boards throwing them this way and that, and although we
could not hear them from our vantage point, it was obvious that the air
was blue with their cuss words. What could possibly cause such a melee?
Many male birds fight in the spring
when testosterone runs high and
females appear to be very attractive. Most are satisfied with posturing
and bluff, however, and blood is seldom shed. It has been suggested
that this behavior evolved to ensure that the most fit males would
father the broods and over time has improved the species. The problem
with assuming that our fight was such a contest is that the combatants
were two females with nary a suitor in sight.
The fact is, the house sparrow is well
known for being a very
pugnacious bird, and it is not the only one. The Indian red jungle fowl
and its descendants that include our domestic roosters, have been
recognized as fighters throughout knowable history. Cockfighting was a
pastime in the Indus Valley Civilization by 2000 BC and the sport was
popular in India, China, Persia, and other Eastern countries by 500 BC.
These cocks seem to possess an almost fanatic inborn aggression toward
all males of the same species and only need to see another cock to
attack and fight to the death.
(Cock fighting was once popular in the
United States but is now illegal
in most areas. Still, in 2009, authorities caught and shut down an
illegal songbird-fighting ring in Shelton, Connecticut that had been
using saffron finches and canaries. The American Society for the
Prevention of Cruelty to Animals commented that such songbird fighting
is extremely rare.)
The house sparrow, commonly known as
the English sparrow to distinguish
it from native American sparrows, is now the most widely distributed
wild bird on the planet. It is about 7 inches long, with a chunky body,
large head and a short tail. The males in breeding plumage have
streaked chestnut backs and heads, gray crowns and black throats and
breasts, while males in non-breeding plumage lack the black throat and
breast and females are a drab, grayish-brown.
House sparrows were originally
introduced in this country to control
caterpillars. They were first released in New York in 1851, in San
Francisco in 1871, and in Salt Lake City in 1873. Since then they have
spread throughout the country and much of the world, mostly due to
deliberate introductions but also through natural dispersal and
seaborne travel. In urban areas, these adaptable birds inhabit a niche
not used by native birds, but in agricultural areas they compete with
the natives for limited nesting cavities and may affect local
populations.
They can survive on city sidewalks or
in farmlands, but avoid extensive
woodlands, native grasslands, and deserts away from human development.
House Sparrows are primarily seedeaters but also eat insects,
especially during the breeding season, as well as anything else
available. They are monogamous and typically breed in open
buildings, nest boxes, or on exposed rafters, but if nothing is
available they will build a nest in a tree or shrub. They frequently
live and even breed indoors, especially in factories, warehouses, and
zoos. A pair typically raises 2 to 3 broods each year.
While the house sparrows seem to fight
much more vigorously, other bird
species also make themselves conspicuous with their springtime actions.
Most of us have probably observed a male robin or cardinal attacking
its image in a window, vehicle hubcap, or other reflective object. An
emeritus biology professor offered this explanation (my shortened
version): This is a territorial behavior where the bird sees an
intruder just its size so it is not intimidated, and will continue to
attack until something intervenes.
I finally broke up the fight on our
front porch as one bird was
obviously getting the worst end of it and I could not watch any longer.
The surprise was that when I opened the door, both flew away seemingly
unscathed, and evidently my concern was groundless. One day perhaps I
will learn to let our wild neighbors live their lives without my
intervention...but I doubt it.
---------------------------------------------
March 2, 2010: Tufted Titmouse
The woods that have been quiet and
seemingly lifeless for the past few
months are showing more signs of spring. The owls were the first to
break the silence and you may have heard the barred owl calling at any
time during the day or night. Then on sunny days, the cardinals began
singing and now the noisy titmice are adding their voices.
The tufted titmouse is a plump
five-inch grey bird, with a lighter
breast and rust flanks, prominent black eyes and a perky crest on its
large head. It is a social bird and, especially in winter, joins with
small mixed flocks of chickadees, nuthatches, and small woodpeckers. It
flits about in the trees and shrubbery, searching upside down as often
as right side up along branches and trunks for insects and other
tidbits. Its song is a loud two-note phrase, repeated over and over up
to a dozen times with the first note high and the second low. Listeners
often describe it as sounding like “pe'-ter, pe'-ter,
pe'-ter”, or sometimes a more melodic "tshew-tshew".
The tufted titmouse was once a
southern species as was the cardinal,
but its range has spread steadily northward throughout the eastern
United States. In the first half of the 20th Century, it was found
primarily along the Mississippi and Ohio River basins, but by the
1970s, it had expanded into New England, the upper Midwest, and Canada.
It has been theorized that this has been possible because of the
growing number of people feeding birds each year, a theory that seems
to be substantiated in our experience, as the birds appeared after we
began to feed. It is a known fact that bird territories depend upon far
more on food availability than temperature. A very similar bird, the
plain titmouse, frequents our son's retreat in the San Bernardino
Mountains but it lacks the rust color on its flanks and black forehead.
I often wondered where the bird got
its strange name but found that it
came from the old English. Titmice have been quite common in Great
Britain throughout history where early on “tit” was a word
meaning “little” and “mase” meant any small
bird. Then, about 500 years ago, the word titmase morphed into
titmouse, presumably because the small, active bird reminded someone of
a mouse, although that seems a bit far-fetched. The
“tufted” description is quite understandable, however, as
the crest on this species is very prominent.
The typical tufted titmouse lives its
entire life within a mile or so
from its birthplace, which is likely to be at a forest edge or in any
grassland as long as there are a number of scattered trees and
sufficient rainfall to allow for abundant insect life. A researcher
found that two-thirds of its food is made up of animal matter, with
caterpillars the largest portion and insects, spiders, and snails
comprising most of the remainder. Tent caterpillars are particular
favorites.
Fruit is also eaten in the summer and
seeds in increasing amounts as
winter approaches. It is interesting that their favorite food seems to
be the acorn when available. One observer reported watching a titmouse
knock an acorn from its twig and then fly down to the ground after it.
The little bird could not open its bill wide enough to grab the whole
acorn, but carried it back up to a limb by its stem. Once there, the
titmouse held the acorn between its feet and hammered at it with its
sharp bill until it had penetrated the shell, and then ate the soft
interior meat in small pieces. Another time, a titmouse was seen
to spear an oak gall more than an inch in diameter on its bill and
carry it to the crotch of a tree where it dug through the tough half
inch of outer covering to reach the white grubs in the center.
After wandering about all winter in
small flocks, the titmice begin
their courtship activities early in spring and separate into
pairs. Many utilize abandoned woodpecker holes for their nests,
but will set up housekeeping in any cavity that is available. Nest
building begins late in April, and they carry in strips of bark and
dead leaves supplemented with moss and dry grass, and then decorate
with bits of rags, strings, or cloth. The nesting cavities vary greatly
in size and shape, which means that in some cases a large quantity of
material has to be collected to fill up the extra space. Titmice are
particularly fond of lining their nests with hair, and collect it from
both dead animals and tolerant live ones. A number of people have
written of seeing one pluck strands from their pets and even from their
own heads as they stood watching.
The birds raise only one brood each
season, and the female builds the
nest and incubates the eggs. The chicks are naked when hatched but are
well feathered and look like adults before they are two weeks old. Both
parents feed the young for some time after they leave the nest, and the
birds travel about together in family groups until they all join the
mixed parties during fall and winter.
Titmice are particular favorites of
mine as they come readily to my
hand for sunflower seeds, peering at my face even as they collect their
prizes. I even read that they can be taught to perform tricks but I am
quite content to enjoy their antics in the wild.
---------------------------------------------------------------
February 23, 2010: The Eastern Grey Squirrel
You may think it is still the dead of winter, but some members of our
wildlife community are already thinking spring. Cardinals are singing
from the treetops, and female grey squirrels have been advertising for
mates, using duck-like “come hither” calls. As soon as an interested
male appears, each doe races off through the branches, leading her
suitors in a wild chase. Eventually, she relents and accepts the most
attractive suitor, and then prepares a warm sheltered nest in a hollow
tree if one is available, or builds a leaf nest if no cavity is handy.
She generally gives birth to two or three kittens in this first litter,
but the second pregnancy that takes place in late spring often can
produce up to six young.
The newborn kits are naked and blind but mature quickly. In eight weeks
the youngsters are venturing out of the nest and by 12 weeks they will
be almost fully grown. An adult grey squirrel grows to about 18 inches
in length, half of which is tail, and weighs between 1 and 1 1/2 lbs.
It is usually grizzled salt and pepper with a white belly but can also
occur in a black color phase. The average squirrel’s lifespan is
normally less than six years, although a few wild individuals have been
found to be as old as 13 years.
The most notable physical feature of the squirrel is its large bushy
tail. This acts as a rudder when the animal jumps from high places, as
a warm covering during the winter, as a counterbalance when walking a
telephone wire, as a signal to other squirrels, and as a distraction to
a pursuing predator. If necessary, a squirrel can lose much of the skin
and even some of the bones of its tail to escape a marauder’s grasp,
and it is not uncommon to see one with only a partial tail. The grey
squirrel has muscular hind legs that allow it to leap more than 20
feet, and long hind feet that are double-jointed and equipped with
sharp claws to help it scramble head first down a tree trunk. If a
squirrel should fall, it can land safely from heights of 30 feet and
more, and we have often seen one just drop to the ground rather than
bother to climb down. When danger threatens, a squirrel will sidle
inconspicuously around the trunk of the tree, keeping just out of
sight. When it remains motionless against tree bark, it is very
difficult to see.
The eastern grey squirrel’s diet varies with the seasons. In early
spring, it eats the buds of hardwood trees, especially maple. During
the summer, maple and elm seeds are major food items, as well as a wide
variety of berries and wild fruits. Squirrels also eat insects,
caterpillars, and will happily clean out a nest of birds’ eggs or young
birds. In the autumn, their most important foods are nuts,
including acorns, hickory nuts, walnuts, and pine seeds. The squirrel's
front teeth continue to grow throughout life, so they can never be worn
away by the animal's gnawing on such hard materials. Squirrels bury
hundreds of nuts and seeds for the winter. They will wait out very cold
weather in their nests, often with others of their kind for warmth, and
then emerge to search for a larder. Contrary to popular myth, squirrels
do not find buried nuts by memory but by their highly developed sense
of smell. Not all hidden nuts will be found though, and some will
germinate and grow into new trees.
It is ironic that although these little rodents cause limited damage in
America, they are considered a major pest in England and Europe, much
as the English sparrow is here. They were introduced there in the late
1800's from North America and their numbers have reached the point
where they have had a noticeable effect on both the bird population and
the general health of the forests. The large population is doing
considerable damage to trees, particularly in early summer when they
gnaw on main stems to reach the sweet, sappy layer beneath the bark,
destroying young saplings and scarring older trees. In addition, Great
Britain’s inoffensive native red squirrel is being squeezed into
isolated areas, not because it is attacked by the grey, but because the
newcomer competes for the food supply and also carries a virus lethal
to the reds.
British grey squirrels have survived repeated government-sanctioned
attempts at extermination by shooting, trapping and poisoning.
Activists paint a bleak picture on one website with these warnings: “
the general public likes the grey squirrel and has no conception of the
damage it does…ignoring the destruction of trees and birds' nests and
the imminent demise of the red squirrel caused by this tree rat…
(The government agencies) appear to accept that the country will never
be able to grow quality timber again, but will the public like to see
woodland reduced to dead and dying scrub?” The projected cost of really
effective control of grey squirrels, however, is extremely high and
perhaps not even possible.
Fortunately, in our country, eastern grey squirrels are only nuisances
when they invade an attic, dig up bulbs in gardens or drive birds away
from feeders. Balancing this is the pleasure they give to numerous city
dwellers, campers, and everyone who enjoys the outdoors. The woods
would be a much lonelier place without their hustle and bustle and
cheerful chatter.
February 16, 2010: The Far-from-tame
Shrew
Winter woes continue to plague us but
it is a comforting feeling to
know that we retirees can sit out any inclement weather, leaving the
running of the country and farm to younger more capable folk. We
continue to worry about our local wildlife, however, and keep our
feeders well stocked.
We were surprised to see a tiny ball
of velvety brown fur scurrying
about by one of the seed piles--a short-tailed shrew. At first glance,
this creature might be mistaken for a mouse, but it is not a rodent at
all but a cousin of the mole, and it was attracted, not by the seeds,
but by the mice eating them. Its round body tapers to a pointed
whiskered nose at one end and a short half-inch tail at the other.
Shrews have poor eyesight, perhaps
because they usually hunt in the
dark underground, but have acute hearing and touch sensitivities. They
are also fierce predators, and someone once said that if a shrew were
as big as a cat, even the largest animal would fear for its life.
Fortunately, most shrews reach only about 5 inches in length including
their tails, while the smaller pigmy shrews are less than 3 inches long
and weigh less than a dime.
The heart rate of a shrew can be as
high as 20 beats per second, and
because of its rapid metabolism, the animal must eat almost constantly
in order to survive. Shrews caught in "live" traps often die before
release due to starvation as they can live only a few hours without
food. They have a three-hour activity cycle, alternating hunting and
feeding periods with sleep, twenty-four hours a day all year long. A
shrew eats several times its weight each day and its menu includes all
kinds of insects, small rodents, amphibians, and even another shrew if
one enters its territory.
Forty of the approximately 290 species
of shrews worldwide live in
North America. Most are terrestrial, living among ground litter in
forests, grasslands, marshes and building nests of leaves, grass, and
hair beneath logs and rocks. Short-tailed shrews actually construct two
kinds of nests; a resting nest and a nursery nest, and the female bears
four or five naked young in May and sometimes another litter later in
the summer. A few other shrew species live in or near the water and it
is an interesting fact that the northern water shrew can run on top of
the water, apparently held up by surface tension.
There are records of shrews in the
earliest documents, including those
of the ancient Egyptians. Together with mongooses, snakes, toads, and
beetles they formed the terrestrial animals "coming from the dark",
while falcons and swifts formed the animals of the light, important
concepts in their religion. Along the Nile the Egyptians built many
animal cemeteries, for which they used the term "resting-places of the
God Osiris-animal" where six species of mummified shrews have been
found.
Ancient Greeks and Romans believed
that shrews were evil. An old text
stated "it containeth in it poison like a spider, and if at any time it
bite either man or beast the truth of this will be apparent...".
Throughout history they have been thought to be poisonous and even
deadly, and English rustics believed that if a shrewmouse ran over the
limb of man or beast, paralysis of that limb followed. Horses or cattle
stiff in the joints or otherwise lame, were asserted to be
"shrew-struck".
We do know that a few shrew species,
including the short-tailed shrew,
produce a toxin, which probably helps to immobilize their prey, such as
other small mammals, reptiles, amphibians, fish and larger
invertebrates, by affecting the nervous system. The bite can also be
quite painful to a human hand for, although shrew's teeth rarely
puncture the skin, the saliva can produce pain and an inflammation and
reddening of the skin that persists for several days. I have handled
these animals several times in the past without a problem, but think I
may be a bit more cautious in the future.
-----------------------------------------------------------
February 9, 2010: The Clever
Blue Jay
Anyone who has delved into bird
intelligence has probably heard about
the carrion crows in California that place nuts on the roadways in such
a way that vehicles crack the shells, and the New Caledonian crows that
have been documented making tools of twigs and leaves trimmed into
hooks. But we have our own species that is closely related to these two
birds—the blue jay.
The family of birds to which blue jays
and crows belong have large
brain-to-body weight ratios, equal to those of the great apes and only
slightly lower than humans. They have out-performed dogs and cats in
experiments testing the ability to seek out food, and some have even
demonstrated the capacity for imagination, something thought to be
unique to humans. This intelligence may be boosted by their chicks’
long periods of dependency, as by remaining with the parents, the young
may have more opportunities to learn necessary skills. Inquisitive
fledglings often seem to play with brightly colored or reflective
objects, such as bottle caps or pieces of aluminum foil, carrying them
around.
The blue jay is white underneath with
a black collar which extends to
the sides of the head, and sports various shades of blue, black, and
white on its back. As with other blue-hued birds, the blue jay's
coloration is not derived by pigments, but is the result of light
interference due to the internal structure of the feathers. If a blue
feather is crushed, the blue disappears as the structure is destroyed.
There is a crest of feathers on its head which may be raised or lowered
according to the bird's mood: when the bird is excited or aggressive,
the crest may be fully raised; when the bird is frightened, the crest
bristles outwards; when the bird is feeding or at rest, the crest is
flattened to the head. Males and females are nearly identical except
that males are slightly larger.
The blue jay prefers forest edges.
Although it will eat all sorts of
plant material— corn, seeds, berries and other fruit—its favorite food
is the acorn, and it will often be found near oaks, in forests,
woodlots, towns, cities, parks. It also is known to eat large insects
and rodents, and some say, if given the opportunity, it will raid a
nest for eggs and young birds but that is disputed. The blue jay stuffs
extra food items in its throat pouch to carry away and hide. It
compulsively buries hoards of grain, nuts and acorns, or hides them in
knotholes and behind loose bark. One study of six jays outfitted with
radio transmitters found that each stashed from 3,000 to 5,000 acorns
in a single autumn. Many of these are forgotten and left to the mice
and squirrels or serve to grow into trees, thus replanting the forest.
A jay has been observed to wait and
watch a person eating at a picnic
table, and if his attention is drawn elsewhere, the bird will swoop
down and steal his food. In fields and gardens, they have been seen to
watch seeds being planted and then dig them up after the planter has
left. Blue jays will also steal foods from other birds by frightening
them into dropping what they are carrying. One captive blue jay used a
scrap of newspaper from the bottom of its cage to reach a pile of food
pellets that lay outside the cage, just out of reach of its beak. Most
interesting, several other captive jays that watched this one method of
problem solving soon used it too. Great apes are the only other
non-human animals besides this family of birds that are known to use
tools in such a fashion.
Blue jays form long-lasting, pair
bonds that usually last until one of
the pair dies. The mating season begins in mid-March with bobbing
displays, courtship feedings and bill-tapping rituals and both build a
loose and untidy nest of barks, twigs, leaves, and grasses. Both
incubate and care for the 4-6 chicks and after they fledge, the family
travels and forages together until early fall. In contrast to many of
our songbirds, the jays seldom raise more than one brood each year.
The blue jay is very noisy, aggressive
and territorial, driving any
intruders (even human) away from food sources and its territory. It
makes a number of different calls including its distinctive "jay- jay,"
a call that seems to attract other jays to join a flock or serves as an
alarm call. It also growls, whistles, rattles and chatters. Another
call sounds like a rusty pump handle, and still another sounds like a
bell. It is quite talented at imitating other birds like the red-tail
hawk, and other odd noises such as machinery, and even human speech.
One interesting behavior shown by jays
is "anting." A bird will take an
ant in its beak and rub it across its wings and in amongst its
feathers, obviously with great enjoyment. Scientists don't have a
convincing explanation for this intriguing behavior, though they have
suggested the ant may give off secretions that might clean the feathers
or soothe the skin, or perhaps repel parasites. Blue jay ingenuity is
represented through its feeding skills, ability to remember hidden
caches, use of tools, and group behavior. It is a bird well worth
watching.
February 2, 2010: White Tails
What is fast as a speeding bullet
(well maybe can go 40 miles per
hour), can jump 9-foot fences with a single bound, swim 13 miles per
hour for several miles, crawl on its belly to hide from a pursuer, walk
on its toenails, smell with a thousand times more sensitivity than a
human, grow a new set of branched bones from its forehead every year,
form the basis of a $250,000,000 business in the state, and also be a
significant cause of high blood pressure and angry arguments?
White-tailed deer can be found from
northern Canada to the Amazon
River, and although their size varies with the climate, one may weight
as much as 200 pounds in Wisconsin, or even larger. It usually travels
in a female-led family group and may live to ten years or more. In
heavily hunted areas, however, most bucks and many does don't live much
past 2 1/2 years of age.
Deer have hooved feet, slender bodies,
and long, thin legs. Ancestors
of our modern deer actually had five toes. Through the ages the first
toe disappeared, the second and fifth toes became dewclaws, and the
third and fourth toes enlarged to form hooves. As a result, deer
actually walk on their toes or, more accurately, on their toenails.
Like our fingernails and toenails, hooves are composed of keratin.
A whitetail's coat and color change
throughout the year. During the
summer months, the deer is reddish-brown, and its hair is less than a
quarter-inch long. By August or September it will shed and re-grow a
brown-grey coat more than an inch thick and made up of a dense
undercoat covered with long guard hairs. These hairs are hollow and
provide insulation, allowing the animal to lie on snow without melting
it, as well as creating enough buoyancy for swimming.
A whitetail prefers to live in or on
the edge of woods and if adequate
food, shelter and water are available, it usually remains in an area of
about a square mile. Restricted to prairies, it would not
survive, as it typically hides or sprints, rather than try to outrun a
predator in the open. It can eat a huge variety of plants, but
concentrates on tender shoots and leaves, fruits, vegetables, nuts,
acorns, and grains. In the winter it survives on frozen vegetation that
turns into nutritious silage in its stomach. One plant that a deer
seldom eats is grass as it has incisors (the cutting teeth in front)
only on its bottom jaw, and a cartilage pad on the front of the upper
jaw and this arrangement causes the animal to pull out the grass rather
than to cut it like the specialized grazers do. The tender base of the
grass is more nutritious and more digestible but a deer would not
thrive on grass alone.
The first section of a whitetail’s
four-part stomach functions both as
a storage and fermentation chamber. Here its food is mixed with
bacteria and protozoa that break down cellulose and other plant fibers
into easily digested materials. When a deer feeds, it quickly fills
this chamber and later regurgitates the contents and chews it more
thoroughly. Water floats the food particles into the next chamber where
the digestion continues. The third chamber absorbs the water and
minerals and moves the food into the final section where enzymes are
secreted. Deer digestion is entirely dependent on their gut
microorganisms.
Whitetail antlers are replaced each
year, in contrast to a cow’s horns
that are permanently attached on the animal’s head and consist of
living bone covered with hard layers of skin. During development, the
antlers are very delicate and extremely sensitive to the touch and
damage. Blood is carried by the outer velvet covering to feed the bone
and when the antlers are fully-grown and the velvet rubbed off, the
bone dies. Antlers can grow at the rate of a ½ inch per day, but
any deficiency in protein, calcium, phosphorus or certain vitamins
during spring and summer can affect their growth. Genetics, age,
nutrition, disease, and injury are important contributors to a buck’s
antlers.
A doe chooses the buck she will breed
with, presumably impressed by his
condition and by the size of his rack. She will give birth to up to
three fawns in May, although in very poor years, she might not breed at
all or have just one. For the first few weeks, the mother will hide her
young in secluded spots and return periodically to nurse them. The
fawns are protected by their lack of body scent for the first few days
and their spotted coats help them to blend in with the forest floor.
As autumn approaches and day length
decreases, a buck’s eyes sense the
change and send a message, via the optic nerve, to the pineal gland.
This pea-sized organ at the base of the brain produces hormones, one of
which
controls the amount of testosterone produced. As this
hormone decreases, a thin layer forms beneath each antler, eventually
causing it to detach. Shed antlers are rarely found in the woods as
they are usually eaten by rabbits, mice, and other animals since they
are rich in calcium and other nutrients.
If there is one creature that
symbolizes Wisconsin, it is the whitetail
deer and we certainly hope that it will continue to inhabit our hills
and fields, and even our yards, for many years to come.
----------------------------------------------------
January 26, 2010: Owls
An owl has a great variety of sounds
in its vocabulary and it creates
all of them with a relatively simple apparatus. Almost every bird
(there is an exception to every rule and I understand the New World
vulture is a case in point here) has a voice box or “syrinx” at the
base of its windpipe. This organ, in contrast to that of a mammal, has
no vocal cords, but is made up of thin vibrating muscles that can
change the pitch of any emitted sound by tensing or relaxing. Songbirds
have the most complex voices controlled by as many as six pairs of
minute muscles, but most owls can not only give forth with hoots, but
can also yelp, bark, and give blood-curdling screams and shrieks.
Owls are unique birds. Although they
are classified as raptors, they
are quite different from other birds of prey in their anatomy, feather
structure, and hunting techniques. An owl is noted for its large head
and large eyes that are fixed in the skull, making it necessary for the
bird to rotate its head in order to see to the side. Its flight
feathers have tiny projections on their leading edges that allow for
silent flight, allowing for surprise attacks on prey. It also has a
distinctive facial disk that helps to direct sound towards the ears and
in some species, one ear is situated lower than the other in order to
better locate the source of any sound. All owls cough up compressed
clumps of undigested hair and bone from their prey and these pellets
are often found beneath a favored roosting tree, indicating that an owl
hunts nearby.
We have seen five species here at the
farm: the barred, the great
horned, the long-eared, the eastern screech, and the northern saw-whet.
Perhaps our most common species is the barred owl. It is gray and
heavily striped, with dark eyes, and a yellowish beak. It can be 20”
tall with a wingspan of 40-50” but looks even bigger than it is because
it is so bountifully feathered. As is the case with birds of prey in
general, the female is the largest of the pair, with an average weight
of about a pound and a half while the male averages about eight ounces
lighter. Its calls are distinctive and sound something like
“Hoohoo,hoohoo, hoohoo,hoohoo--aww, with a noticeable drop in pitch
with the last syllable. When excited, one often fills the air with
eerie sounds.
The barred owl nests in March in
Wisconsin, usually in a cavity of a
hollow tree. The female will lay 3-4 eggs several days apart and will
begin to brood them immediately, a behavior which causes the chicks to
hatch over a week or more. This ensures that when food is scarce, the
older stronger hatchlings will have a reasonable chance to survive even
if the smaller chicks starve. The youngsters leave the nest at about 4
weeks but remain on branches nearby until they take their first flights
at about 7 weeks. Parents care for the young for at least 4 months,
much longer than most other owls. Pairs mate for life, and will return
to the same nest site year after year.
Larger than the barred owl and
certainly more fierce, is the great
horned owl, a bird that often has a 4 1/2-foot wingspan. It can easily
carry off a skunk or rabbit, and will kill other owls and hawks if it
gets the opportunity. Nesting season begins in January or February but
the owls often begin courting in December with the pairs hooting to
each other in extended duets. Males have a lower-pitched voice than
females—a series of seemingly soft hoots--but can also make a variety
of other sounds. In silhouette, the tufts of feathers on its head
easily distinguish it from the barred owl.
A few years ago, a pair of long eared
owls took up housekeeping in a
large pine above a neighbor’s driveway. The nest probably would have
remained undetected, but one of the half-grown chicks fell to the
ground and had to be rescued before a cat pounced on it. The adult
long-eared owl averages 14 inches long with a wingspan of about 39
inches, and its "ears” are actually tufts of feathers. The call of the
male in breeding season is often a low, slow "hoo, hoo, hoo, hoo, ...”
repeated up to 100 times, while the female responds with a raspy buzz
call.
Eastern screech and northern saw whet
owls are small and stocky in
comparison to the other owls and they have large round heads—the
screech owl with ear tufts and the slightly smaller saw whet, without.
They both nest in tree cavities, usually old woodpecker holes, but will
sometimes use nesting boxes. The screech owl has either a trilling song
on one pitch, or a descending “whinny”, and has been reported to eat up
to one-third of its own body weight in small animals and birds each
night. The saw whet owl feeds mostly on woodland mice and its call is a
regularly repeated “coo”, thought by some to sound somewhat like a saw
being sharpened.
If you step out doors on a relatively
mild evening or perhaps early in
the morning before daybreak, even now in the dead of winter, you may
hear the hooting of one of these owls. Some of their breeding seasons
are already underway and this may be the only time you will receive
confirmation that these reclusive neighbors live nearby.
-----------------------------------------------------------------
January 19, 2010: A January Thaw
Now that the bitter temperatures have
moderated a bit, animals such as
the raccoons, skunks, and opossums find it possible to come out and
forage for food. You may find one visiting your bird feeders, you may
see its tracks in the snow, or sadly, you may see a body along the road
where one has suffered a collision with a vehicle. Why do they emerge
from snug dens where they were safe and warm? The answer is that in
contrast to those that actually hibernate, these creatures cannot
survive a northern winter without replenishing their inner stocks and
must take advantage of any period of milder weather to hunt.
Raccoons are known to winter together
in communal "piles" of up to 23
individuals in a single den. They use hollow trees, empty buildings,
woodpiles, abandoned badger and coyote dens and sometimes venture into
attics—to the dismay of the homeowner. With the cooler temperatures of
fall, they feed intensively to build fat reserves for winter on
energy-rich foods including nuts and grain such as corn and high
protein foods, until some third of their body weight is stored fat.
They can den for a month or more during severe weather, living off
these stores, but when temperatures moderate, they will arouse quickly
and emerge. At this time, raccoons will hunt for waste grain, carrion
and assorted small animals.
Several skunks, usually a single male
and several females, often share
a winter den, plugging the entrance hole with nesting material. They
huddle together to share body warmth and live on stored body fat, while
solitary skunks usually must undergo daily torpor to conserve energy to
survive. Skunks come out during warmer periods to feed, raiding garbage
cans, hunting mice, and eating virtually anything they can find. They
will also take the opportunity to breed.
As recently as the early 1800’s, the
opossum was not found in the upper
Midwest and was mostly thought of as a southern species. Its territory
has kept expanding, however, and today it can be found into northern
Minnesota and Wisconsin. Opossums are not well adapted to life in
northern latitudes as they have no fur to cover their tails or their
ears leaving these two areas prone to frostbite, and since they don’t
hibernate, the search for food and water during the cold winter months
often leads this animal outdoors during poor conditions, causing frozen
extremities.
The opossum is North America's only
marsupial; that is, the female
carries her newborns around in a belly pouch. These animals have
been dated back to the time of the dinosaur, and the species has
survived virtually unchanged for over 60 million years. The opossum
will eat almost anything, including food scraps in garbage, insects,
rodents, bird eggs, fruit, and acorns. In the fall, opossums devote
much time to feeding, adding a layer of winter fat, but they do not
grow winter fur and their normal coat provides poor insulation. In
February and March, opossums also become active in search of mates.
All of these animals increase their
weight in the fall by accumulating
fat, but in contrast to us humans, much of their fat is brown. Everyone
is familiar with white fat tissue which provides insulation and, by
storing triglycerides, serves as an energy depot. Triglycerides play an
important role in metabolism as they contain more than twice as much
energy potential as carbohydrates and proteins. Still, despite its
value, most of us accumulate far too much white fat and spend much
energy and money trying to avoid or eliminate it from our bodies.
Brown fat, on the other hand, is quite
different and its primary
purpose is to regulate body temperature. Brown fat tissue contains a
much higher number of fuel cells called mitochondria (which contain
iron and make them dark red to tan), and they are designed to burn high
quantities of sugar--the body's fuel--and release that energy as heat.
Brown fat also contains more capillaries than white fat, since it has a
greater need for oxygen than most tissues.
Raccoons, skunks and opossums are well
supplied with brown fat, and it
takes the form of two large masses on the back between the shoulder
blades with additional amounts around the aorta and the kidney. This
brown fat generates heat that is sufficient to keeps the adjacent
internal organs if not actually warm, at least able to function.
Research has found that the heat-producing breakdown of the brown fat
is so effective, that a well-fed tiny shrew can actually gain weight
during winter. It has also been shown that its brown fat reaches
its maximum heat-generating capabilities in mid-January, when the
outside temperatures are coldest.
It has long been known that human
infants possessed brown fat to help
them stay warm but now multiple studies in The New England Journal of
Medicine tell us that brown fat is also present in adults. They suggest
that it may prove to be of help in a potential treatment for obesity,
and point out that cold temperatures, particularly during short winter
days enhance its fat burning action. Until a magic pill for weight loss
is developed, therefore, perhaps we, too, should spend more time
outdoors this winter.
----------------------------------------------------------
January 12, 2010: Food for the
Birds
We have fed the birds in the winter
for 50 years but this is only the
second time we have had to get out early in the morning to replace the
seeds eaten overnight by deer. The deep snow has obviously made life
difficult for what few white-tails still remain and they visit us
several times a day and clean up the sunflower seeds. We like to watch
them but worry about their survival under such difficult conditions.
Did you know that over 100 North
American bird species supplement their
natural diets with birdseed, suet, fruit and nectar obtained from
feeders? Many people simply put out small hanging dispensers purchased
from a hardware or variety store and filled with an inexpensive seed
mix. However, to attract and keep a diversity of birds, the more
knowledgeable bird lover will provide three essentials: quality food
offered in a suitable manner, fresh water for drinking and bathing, and
sufficient cover.
Most of what we know about the most
efficient and economical methods of
backyard bird-feeding comes from the work of Dr. Aelred Geis, who first
served at the U.S. Fish and Wildlife Service Patuxent Wildlife Research
Center in Laurel, Maryland and then as Director of Research for Wild
Bird Centers of America. His research examined the relative
attractiveness of various foods to wild birds in California, Ohio,
Maine and Maryland, collecting data from widely separated areas to
determine if there were regional differences in bird food preferences
but finding none. He did observe that many commonly used materials in
inexpensive mixes such as wheat, cracked corn and milo had very little
appeal for the birds and could well be left out. Dr. Geis died in 2007
at 78 but his findings are still the basis for most of what we know.
Dr. Geis found that sunflower seeds
were the most beneficial and widely
accepted bird food. The form commercially marketed for birds tends to
have relatively small seeds because the larger seeds are reserved by
the industry for human consumption. He advised to choose packages
labeled as oil-type sunflower seeds, as not only are they eaten by a
greater variety of species, but there are from two to four times as
many of these small seeds as the larger black striped sunflower seeds
in packages of the same weight. The seeds can be placed in a hanging or
elevated feeders, as well as on platforms which ground-feeding birds
are more likely to visit. Whole or broken kernels of hulled sunflowers
are also very attractive (although more expensive), and white proso
millet should be offered to the smaller birds by spreading it on the
ground or on a platform feeder.
Peanut hearts, which are the embryos
of the peanuts removed in making
peanut butter, are sometimes added to mixes to make them smell better,
but there is little to recommend them as they were found to be
attractive only to starlings. In contrast, peanut kernels were snapped
up by blue jays and tufted titmice, although both also took sunflower
seeds readily, a cheaper alternative. Rapeseed was only eaten by
mourning doves and house finches, and safflower was initially chosen
only by cardinals and mourning doves as well as an occasional sparrow.
Additional tests indicated that several species gradually increased
their intake of safflower and that it might be used to feed cardinals
while discouraging other undesirables. Niger (also called thistle seed)
was very attractive to goldfinches, but it was suggested that this was
because they did not have to compete with other more aggressive species
at its specialized containers. Goldfinches very well might prefer the
oil sunflower seeds if offered in such a manner that other birds could
not crowd them out.
The greatest variety of bird species
was attracted to food placed on
the ground, or for practical reasons, platform feeders. It is because
of this fundamental bird behavior that large feeding tables were used
in studying the relative attractiveness of various foods in Dr. Geis’s
research. They simulated ground feeding in order to obtain data on
species such as juncos, which do not like to use elevated feeders, and
the larger species that cannot use perches. It was reported that
placing white proso millet on the ground next to dense cover resulted
in attracting many species of birds including some that were rarely
seen on elevated feeders. At the same time, tube feeders without trays
benefited those birds capable of clinging -- finches, chickadees,
titmice and woodpeckers.
We know that some birds, notably
cardinals, mockingbirds and tufted
titmice, have extended their winter range northward, most likely
because of the increased availability of food in our backyard feeders.
However, we must also keep in mind that bird feeders do present
potential risks to their visitors, such as window collisions,
predators, and possible disease. A recent study found that colliding
with a window is the most common cause of bird death associated with
feeders, with predation by cats a close second. By keeping your cat
indoors, you will not only protect birds, but also keep it safe from
traffic, disease, and fights with neighborhood pets and wildlife. It is
also important to keep your feeders clean as any situation that brings
many creatures into close contact has the potential for spreading
disease.
_________________________________________
January 6, 2010: Cold Birds
The birds arrive at the feeders at
first light these frigid days, eager
to replenish their dwindling reserves of energy. Birds have
greater resistance to cold than mammals but their metabolism is very
high and they must eat regularly and often to fuel their little
furnaces. The body temperatures of the various species range from 101
to 112 degrees F, the higher numbers belonging to the tiny birds such
as hummingbirds that must eat almost constantly. In fact, only the core
of the body need be maintained at these temperatures and the
extremities can be allowed to cool somewhat without significant harm.
Heat losses from their bodies are kept
to a minimum by coats of
feathers which insulate them with trapped air, legs and feet that have
no exposed fleshy parts, and bills that are composed of horn-like
tissue. A bird’s feathers are arranged in such a way that an outer
layer of the contour feathers provides a streamlined, sleek outer
covering over a layer of air-trapping down. Contour feathers have a
small downy portion closest to the skin; semi-plumes are virtually all
downy; and down completely lacks any interlocking barbs. This
arrangement provides excellent insulation, so long as the wind doesn’t
get beneath the feathers. Insulation can be increased by fluffing up
the feathers to increase the amount of trapped air.
Birds have a number of ways to
conserve body heat. They may tuck
their bills as well as one or both feet up into their feathers when
perching, and may shiver for short periods to convert muscular energy
into heat. In addition, most birds have air sacs under their
skins that help to insulate their inner workings. Many waterfowl also
have a remarkable adaptation, as the arteries and veins in their legs
lie against each other, the arterial blood warming the cold blood
returning from their extremities. Large birds have an advantage over
small ones because they have relatively smaller surface areas that lose
heat.
High metabolism gives a bird quick
energy for moving around, for
reproduction and growth, for the repair and molting of its feathers,
and for warmth to survive winter cold; but it demands that birds keep
taking in carbohydrates, fats, and proteins. They must eat foods rich
in potential energy such as seeds, nectar, fruits, insects, and
rodents, and their bodies must make efficient use of the food with
relatively little waste.
Some species have additional survival
techniques. Many birds have high
concentrations of glucose in their blood, up to double that of
humans. Evening grosbeaks and some other northern finches are
able to store relatively large amounts of seeds in their crops, a
strategy which seems to be effective in maintaining high metabolism
overnight. (A bird's crop is a sac of muscle tissue in the esophagus
that it uses to store and soften its food before it moves on to be
processed by the gizzard.)
Many birds roost among the thick
branches of conifers and other trees
that hold their leaves into the winter months. Particularly when
snow-covered, these provide protected cavities out of the wind and
wet. Chickadees, woodpeckers, and nuthatches sleep in holes in
trees while bluebirds have been observed to pack together with up to a
dozen or more individuals stuffed into one birdhouse. A Russian
study found that two birds huddled together at zero degrees F reduced
their individual heat losses by 23% while a group of three each reduced
its loss by 37%. Ruffed grouse sometimes plunge under loose snow
where temperatures have been measured to be as much as forty or fifty
degrees warmer than at the surface.
Although some species have white
feathers presumably to blend into a
snowy landscape and so avoid the notice of a predator, the backs of
most winter birds are dark to more efficiently absorb any warmth
available from the winter sun. Last week, we saw a collection of what
looked to be tree stumps on a south-facing hillside that proved to be a
large flock of black turkeys, hunkered down and taking advantage of the
sun’s rays.
Our winter nights are about 15 hours
long and day-feeding birds must be
able to endure the cold for this length of time without food.
Experiments have found that small birds could survive up to three days
during the summertime but as the temperatures dropped so did their
ability to resist starvation. At 5 degrees above zero sparrows
could live without food for 15 hours, but at -20 degrees most could not
live more than ten hours. At -30 degrees they survived only about
seven hours, so it is obvious that on frigid nights they must find
sheltered roosts and have full stomachs.
We can help all the birds by keeping
our feeders well stocked,
especially late in the day, and providing some sort of nearby
protection from the wind.
------------------------------------------------------------------
December 29, 2009: Red-tailed
Hawks
The big oaks across the way are now
leafless and bare, and we can again
see the big nest usually hidden high in the branches. A pair of
red-tailed hawks built it years ago and it has been refurbished and
used off and on many times since. We think two babies were successfully
reared there this past summer as they made their presence known, first
by squawking demands to their harried parents, and later by their
awkward hunting techniques.
The red tail is our largest hawk,
usually weighing between 2 and 4
pounds. As with most birds of prey, the female is nearly a third larger
than the male and may have a wingspan of 56 inches. The adult is easily
identified as it soars overhead, showing its broad, rounded tail that
is a rich, russet red. When perched, you may be able to see its dark
brown back and wings, and a white chest streaked with brown. There is
also a broad band of dark streaking across its white belly that looks
like a brown crescent. The immatures resemble the adults except their
tails are brown with dark bars, as they do not get red tails until they
molt during their second year.
Hawks are meat eaters who belong to
the category of birds known as
raptors. All have strong, hooked beaks and long, curved sharp talons.
Prey is killed with the talons and if it is too large to swallow whole,
it is torn to bite-sized pieces with the beak. The larger hawks can eat
an animal as big as a rabbit but usually settle for smaller rodents, as
well as small birds, large insects, reptiles, amphibians, and some
carrion.
Based on general body shape and flight
habits, hawks are classified
into three different groups: the accipiters, the falcons and the
buteos.
The sharp-shinned hawk, the Cooper's hawk and the goshawk are
accipiters, and all have long tails and short, rounded wings that
enable them to dart through and around trees in pursuit of other birds.
Falcons have streamlined bodies, long, pointed wings and long tails and
include the peregrine, the merlin, and the little American kestrel,
also called the sparrow hawk. The buteos are the broad-winged,
broad-tailed soaring hawks that include the red-tailed, the
red-shouldered, the Swainson's, and the rough-legged.
The red-tail establishes and protects
a territory of up to four square
miles, the size dependent on the availability of prey. It often hunts
by soaring high in the sky, using its keen eyesight to spot the
slightest movement in the grass below. It has eyes as large as those of
an adult human but reportedly eight times more powerful, and a hawk can
track a mouse while more than 100 feet above the ground. When it
identifies prey, it dives, extending its legs with spread claws. As it
strikes, the toes and talons are automatically clenched, piercing the
vital organs of the victim and causing instant death. At other
times, the red-tail watches for prey from a perch in a tree or atop a
utility pole. When it spies movement, it takes off with powerful wing
beats, then glides downward and snatches its prey from the ground or
kills and eats it on the spot.
Mating and nest building begin in
early spring and are accompanied by
spectacular aerial displays by both males and females. Circling and
soaring to great heights, they fold their wings and plummet to treetop
level, repeating this display over and over. Both participate in
building or rebuilding the nest -- a large, flat, shallow structure
made of sticks and twigs. Nest sites may be used repeatedly, but new
layers of nesting material are added each year. The female usually lays
two or three whitish eggs that are marked with reddish spots and
splotches. She incubates the eggs for four weeks, during which time the
male hunts for both of them, bringing her food to the nest.
When hatched, the young are covered
with white down and are helpless.
After a week or so, they have developed enormous appetites and the
female leaves the nest and helps her mate search for food. The young
can fly when they are about 45 days old and play games of plunging and
veering, practicing their hunting skills while they cavort. Their
parents continue to find prey for them for many weeks until they have
gained the coordination and experience needed to capture their own.
As early as 680 BC, Chinese records
describe falconry -- the practice
of using raptors as hunting aids – and the last 30 years have seen a
great rebirth of the sport. Among North American raptors, some of the
most popular birds used are the red-tailed and Harris hawks, the
peregrine falcon, and the goshawk. The chicks are obtained from captive
breeding programs and practitioners spend long hours taming and
training the birds. Besides competing at game fairs and using the birds
in private hunting, falconry is used in managing pest birds and animals
in urban areas, landfills, commercial buildings, and airports. On the
farm, we treasure their presence, not only for their help in
controlling the rodent population, but also for their beauty and grace
as they soar overhead in the sky.
--------------------------------------------------------------
December 22, 2009: Where Have
All Our Wild Family Gone?
Our farm is home to thousands of
species of wildlife during the summer
months. Many of them are firmly rooted in the territories where their
families have lived for many generations while others come and go
following their own agendas. It is fun to conjecture just where all of
these various “family members” are right now, as we sit snug and warm
in our living room.
A great majority of the mammals never
stray far from the area, many
taking shelter underground, and while a few are hibernating, most have
just retreated to wait out the inclement weather. Others remain active
and we see and hear them or find their tracks in the snow as they go
about their lives. Deer, coyotes, foxes, rabbits, and weasels must eat
year around and are almost always on the move.
The birds, of course, are the widest
ranging, and many have traveled
thousands of miles since we last saw them. The killdeer, woodcocks, and
whip-poor-wills are probably down near the gulf coast, in Florida or in
Texas. Also making that trip, although they may have stopped at
inviting spots along the way are the phoebes, sapsuckers, kingbirds,
tree swallows, wrens, catbirds, and kinglets.
If the fact that a tiny bird can
travel south a thousand miles and find
its way back again is amazing, how much more so is the knowledge that
many other species cross the Gulf and often keep going. The
ruby-throated hummingbirds that sipped from our feeders all summer are
probably now in Central America, while the bobolinks from our upper
field are even further down in South America. The northern orioles that
nested in the big willow are now basking in the tropics, and the yellow
warbler that sang in the big oak along the road may be in Peru.
The scarlet tanagers may be splashing
in the Amazon River, and the
indigo buntings could be flying about in the West Indies. On the other
hand, robins, geese, bluebirds, meadowlarks, some of the warblers and
many of the sparrows probably went no farther than necessary to escape
the worst of the winter weather, and a few may be hanging around in
protected spots here in the state. I have heard robins scold in the
woods in the middle of January, perhaps announcing that they had no
plans to leave unless forced by a lack of food.
The monarch butterfly that we watched
emerge from a chrysalis last
September may have caught a strong north wind and made its way into
Texas or even Mexico. Most of the other species of adult insects that
will survive the winter, however, are snugly tucked into some crevice
or under a stone or log where they have become dormant and frozen until
spring breathes new life into their seemingly lifeless bodies.
The spring peepers and other treefrogs
are also probably frozen, lying
hidden in the leaves and brush in the woods. How the bodies of
these amphibians can thaw unharmed when spring arrives is another of
those mysteries of life that scientists and we laypeople find so
fascinating. It is known that they accumulate a considerable
quantity of glucose in their cells which seems to act as an antifreeze,
and that water in their body cells migrates out into the spaces between
them, but just how the process can work as it does is not fully
understood. Most other frogs and toads spend the winter
underwater in the mud of the pond or buried deep in the soil in the
woods, as their bodies are not able to withstand freezing and so must
somehow reach frost-free spots.
The snakes take shelter in tunnels
below the frost line that were
acquisitioned from a variety of excavators that may or may not have
given up ownership willingly, as they cannot survive freezing either.
We have an ancient oak stump that has harbored a variety of these
reptiles for years, and I have always wished that we could thread a
tiny camera down into one of the many tunnels beneath it and see what
is hidden there.
All of our extended family will be in
our thoughts this holiday season
wherever they may be, and as we give presents to relations and friends,
we will also fill the feeders as a gift to those wild creatures that
give us pleasure all through the year. Merry Christmas.
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December 15, 2009: Antlers or Horns
Most hunters we know enjoy the meat of
any deer they bag, but it is
taking an animal with a rack of large antlers that causes them to brag.
What is it about these strange projections that makes them so prized?
Most large grazing animals have either horns or antlers that are used
for defense and in duels between males for possession of a female.
Although both have a similar purpose, they are very different
structures. Most cattle, sheep and goats have horns. These are hollow
horny sheaths made of keratin, the same substance as our fingernails
and enclose pointed bony cores that arise from the front of the skull.
Horns are unbranched, are never shed, are commonly found on both sexes,
and continue to grow throughout the life of the animal.
Antlers, on the other hand, are
usually found only on male deer and are
the fastest growing tissue known. They begin to develop in early
spring, starting as soft, swollen pads on the skull and lengthening
into club-like structures. Antlers are live tissue, composed of bone
and growing at an average of 1 to 2 inches per week. During this time,
they are covered with a soft brown-haired skin called "velvet" that
protects the many tiny blood vessels that carry food and minerals to
the growing tissues. Antlers in velvet are delicate and easily bruised
and will bleed if scraped against a tree or branch.
Its first fall, a young buck will grow
small bumps, called buttons, and
by the second fall, it will usually have one or two points on each
small antler. At 2 1/2 years, a buck will usually have 3 to 5 points on
a side, and a mature animal will usually grow medium to large antlers
with additional points. A popular belief is that you can tell a deer's
age by the number of points on each antler, but the only true way to
tell a its age is by its teeth, as the size and shape of the antlers is
greatly influenced by genetics and diet.
During the summer when a buck's
antlers are growing, they act as air
conditioners to help get rid of extra body heat. Then, after three or
four months, the blood supply is cut off and the antlers harden. The
dead and dry velvet peels off in strips, helped along by vigorous
rubbing against trees and other sturdy uprights. During mating or
rutting season, a buck uses his antlers to fight other males, lunging
at any intruding stranger head on and sometimes even locking antlers.
After a few minutes of shoving and pushing, during which pieces of
antler may be broken, the weaker male will usually retreat, leaving any
nearby females to the victor. After the breeding season in January or
February, bucks will shed their antlers, the growths separating easily
from the skull bone and leaving smooth scars with no jagged edges. The
discarded antlers are a welcome treat for mice, chipmunks, squirrels,
and porcupines because they contain calcium, salt, and other minerals.
Prehistoric man used horns and antlers
as tools, but they were also
utilized in medical treatments in the Orient. The first written
reference dates back to a scroll from the Chinese Hun Dynasty, 206 B.C.
to 200 A.D., in which deer antler velvet was recommended for 52
different diseases. Chinese medical books claimed that the substance
helped the kidneys, improved lung function, increased vitality,
improved circulation, and sharpened mental awareness, among other
things.
The term velvet originally referred to
the fine hairs on the antler,
but is now used specifically to indicate its immature stage before it
calcifies. It has a cartilage-like texture and has a velvety feel.
Velvet antler calcifies from the bottom up to the top and it must be
harvested at the right stage, usually from a living animal that is not
harmed by the operation. It is then dried and sliced or powdered. The
most common use is for relief of rheumatism and arthritis, but it is
also used for a variety of other purposes, ranging from sexual
disorders to enhancing athletic prowess. Ossified antlers that fall off
naturally are still valued but must be boiled to yield a gelatin that
can be used for certain applications, such as easing swelling.
Today, there are some 35,000 deer
farms in Korea, New Zealand, China,
Russia, Mongolia, and, more recently, the United States. They produce
animal meat to be used as food, and antlers that are usually exported
to the Orient, though antler-based health products are now manufactured
for domestic consumption around the world. Traditionally, deer antler
is sliced very thinly or ground to powder. The thin slices are made by
removing the outer, hairy portion of the antler, soaking the antler in
hot alcohol to soften it, and then carefully slicing it to produce
round wafers. The slices are best suited for soaking in wine to make a
"tincture" of antler. Very thin slices can be eaten directly. To make
gelatin, ossified antlers are boiled for several hours to release the
gelatin that also can be dried and ground into powder, and consumed
directly.
According to one internet source, the
old deer horns have become the
latest aphrodisiac craze in California. Only the tips of the horns are
used and make a powder that is then pressed into pills. While there is
no scientific evidence regarding any supposed benefits, it doesn’t
bother the deer as they have already discarded the antlers, and its use
is both legal and safe. I think I’ll leave any antlers I find for the
mice, however.
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December 8, 2009: Why Flocks?
One of the questions that has nagged
at me for years is why some birds
spend so much of their time in large flocks. It would seem that
competition for food would be very great in such situations and disease
would spread rapidly. Still, it is a common sight to see sizeable
groups of blackbirds and starlings almost year round, and the past few
weeks there have been impressive flocks of large birds visiting the
fields on both sides of the road on any drive to Madison.
Some of the first to appear were the
sandhill cranes – family groups
feeding in pastures and open fields – and then congregating in
ever-increasing flocks as the fields were harvested. Sandhills, tall
gray birds with wingspans of 6-7 feet, gather together in groups of
several thousand to migrate to Florida where they spend the winter
months. In the 1800s, the populations of sandhill cranes dropped
drastically from habitat loss and over hunting, but in 1916, the
federal Migratory Bird Treaty Act was signed, protecting the remaining
birds and the population is now in good shape.
(Sandhills are one of two crane
species found in North America, the
other being the whooping crane, an endangered species that has recently
been reintroduced to Wisconsin. If you have not been watching this
year’s class of young whoopers being led to Florida by ultralites, you
might be interested in their progress. They began their journey on
October 16th, but poor flying conditions resulted in slow progress
until the last week or so. At this writing they are in Tennessee –
about half way -- in contrast to the first two years when they had
reached Florida by the first of December.)
Flocks of Canada geese are more
noticeable as they fly in V-formations
overhead or rest in large numbers on the banks of ponds and creeks.
Each spring and fall, hundreds of thousands of these geese pass through
Wisconsin, mostly members of the Mississippi Valley population that
nest in north-central Canada along the shores of Hudson and James Bay.
There are more than 1 million Canada geese in the MVP, with about
100,000 - 200,000 stopping at Horicon Marsh each fall where they often
stay for a month or two to refuel (each goose eats about ½ lb.
of food per day). They then continue their migration to wildlife
refuges in southern Illinois, western Kentucky and Tennessee. In
Wisconsin, you may see two main sub-species of the Canada goose -- the
"interior" type that just pass through, while the "giants" are commonly
seen year-round in towns and cities just hanging out at any water and
open areas with mown grass. This city goose population is growing fast
since some people like to feed them, and in many places they have
become a definite nuisance.
A third large group you may see are
gulls, usually herring and
ring-billed. Misnamed as seagulls, these birds often feed in farm
fields, eating insects and worms. Herring gulls with a red spot on the
bill are the larger, but ring-billed gulls are often the more numerous
in our area. These birds eat a great variety of foods and will often
scavenge from garbage dumps and landfill sites, with refuse comprising
up to half of the bird's diet. The survival rate for inland gulls is
much higher than their counterparts in coastal areas, with an annual
adult mortality rate of less than 5%. It is also common for each female
to successfully rear three chicks per year. This has resulted in a
massive increase in numbers over a relatively short period of time and
led to the big flocks we are seeing.
We have long been told that birds
flock to enjoy certain benefits: that
is, they gain safety in numbers and increased efficiency in finding
food. Defense against predators is particularly important in forests or
other dense cover where predators can hide. In the winter, small
insect-eating birds, often led by chickadees and titmice, move about in
mixed-specie groups, presumably since early warning provided by
multiple eyes is important. This does not explain the huge flocks of
bigger birds out in the fields, however.
Now, neurobiologists at Indiana
University have come out with an
interesting theory on flocking. They report that all vertebrates
produce oxytocin, a hormone that is best known for its role in female
reproduction but that also relays and amplifies nerve signals in the
brain. When they blocked the actions of the hormone in female zebra
finches, the birds became much less social and gathered in smaller
groups, while the opposite was true when the hormone was increased.
The scientists then speculated that
some bird species flock while
others don’t because they have varying numbers and arrangements of
receptors for the oxytocin in the brain. The authors mapped this
distribution using a radioactive compound in three finch species that
form flocks and two that don’t and found that the flocking species had
many more receptors in specific areas. If this discovery holds true for
other birds and even mammals, the concentration of receptors for
oxytocin in the brain could accurately predict whether an individual is
naturally gregarious, and the study goes on...
_-----------------------------------------------------------------
December 1, 2009: Wolves, Cougars and
Bobcats: Oh No!
The most hazardous period in the life
of a wild animal, providing it
survives infancy, is when the time comes when it must leave its mother
and strike out on its own. Mice and other small species must do this
only weeks after birth. For many medium-sized species such as the
woodchuck, skunk, and fox, this usually comes some time during their
first autumn. For larger animals, the young often remain with a parent
through the first winter and sometimes don’t leave until they become
sexually mature. Whenever it comes, dispersal is almost always vital to
the survival of the species because too many animals in one place can
lead to starvation, disease, and struggles for dominance.
Ideally, about the same number of new
individuals in a species become
adults each year as are needed to replace older members who have died.
Any excess typically succumbs to hunters or becomes food for other
animals, but some may try to move into new territories. These moves are
seldom successful, unless some change has occurred in the environment
of the new habitat to give them an opening. Sometimes it is grassland
that grows up into forest, or conversely, forest that is converted into
grassland. Or perhaps another species or crop has been introduced that
provides suitable prey, or the animals themselves are able to adapt to
new conditions.
There has been some concern among some
members of our community that
coyotes have expanded their numbers and begun preying upon pets in some
locations. Of course, one simple reason for this is that we have built
more and more homes in the coyotes’ territories and, always
opportunists, they welcome this source of easy food. Every year,
however, there is reason for far more worry as larger predators from
farther north are moving in.
The closest wolf packs now operate in
Juneau, Adams, and Monroe
Counties and dispersing young animals are becoming more common in our
area each year. Husband Bill saw one here on our farm several years
ago, only to have it killed on a nearby highway a few days later. Many
make their way even farther south and a young wolf was found down in
Illinois some 500 miles from its birthplace. Although wolf populations
may fluctuate from year to year it is estimated that over 550 wolves
now live in the state, far more than the target numbers that were
determined to be tolerable. While the rebounding wolf population is an
ecological success story, it undoubtedly will create problems for
farmers who lose livestock and pet owners who suffer losses.
Not only young adults but also female
bears with cubs and yearlings
have been reported the last few years in the area, according to Spring
Green DNR biologist Becky Roth. She says “The wooded hills, coulees,
creeks and river bottoms in southwestern Wisconsin’s Driftless area
provide abundant food and cover for bears as well as potential winter
den sites, so it’s possible that wandering bears will find it to their
liking and some may decide to stay”.
There were once three wild cats native
to Wisconsin – the cougar, the
bobcat and the Canada lynx. The only recent report of a cougar came on
January 18, 2008 when one was sighted and verified near Milton, in Rock
County, and tracks were found near Elkhorn, about 23 miles southeast.
An adult male can weigh up to 160 pounds, and reach 95 inches in total
length, while females are somewhat smaller. Tracks of cougars are
usually about 4.0 inches across with no claws.
Biologists don’t think that the lynx
are breeding in Wisconsin either,
so all the sightings are probably just visitors, not residents. The
last dead lynx found in Wisconsin was picked up near a highway in 1992.
That same year a hunter mistakenly shot a lynx in northern Wisconsin.
Currently bobcats are the only known
breeding wildcats in the state,
with a fall population of about 3000 in northern Wisconsin. A bobcat is
about twice the size of a large house cat and usually weighs 20 to 30
pounds. It has a tan to grayish-brown coat streaked with black
and dark bars on the forelegs and tail. It has yellow eyes and its ears
are black-tipped and pointed, with short black tufts. An adult is
usually about 35 inches long with a stubby 6-inch tail that has a
"bobbed" appearance.
I have heard a number of local rumors
of bobcat sightings and had
always assumed that they were residents in our area, but if the DNR
information is correct, these, like most of the wolf and bear
occurrences, were probably also visitors. Still, with these larger
predators moving south and reportedly even settling in, we will do well
to keep our eyes open and senses alert to the possibility of having one
in our own back yard.
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November 25, 2009: All About Turkeys
Thanksgiving and turkeys have been
almost inseparable throughout our
country’s history. William Bradford of Pilgrim fame wrote an account of
the Plymouth settlement some 22 years after the fact, but the document
was captured by the British during the War of Independence and carried
back to England. It finally came to light in 1854 and his descriptions
of the colony and their first thanksgiving feast eventually led to a
proclamation by President Lincoln that we celebrate a national holiday
in remembrance. Although there is no solid evidence that turkey was
served at the Pilgrims’ meal, it later became an indispensable part of
the Thanksgiving tradition.
The Pilgrims were probably familiar
with two types of turkey – the wild
bird that was a staple of the native people living in that area and the
domestic turkeys that they reportedly brought with them on the voyage
in 1620. These were descendants of wild birds domesticated by native
Mexicans and carried to Europe in 1519 by the Spaniards.
All domestic
turkeys have white-tipped tails, a characteristic that now
distinguishes them from wild turkeys, although diet, lifestyle, and
breeding have changed them in numerous other ways.
Domestic turkeys weigh twice what a
wild turkey does, and almost all
are bred to have white feathers because their pinfeathers are less
visible on the dressed bird. Breeder farms supply eggs to hatcheries
that deliver the hatched poults to grow-out farms. There they are
separated by sex and fed carefully designed rations. The hens are
harvested at about 14 weeks, and toms at about 18 weeks. Mature toms
are too large to achieve natural fertilization, so their semen is
collected and hens are inseminated artificially. The turkey is a
popular form of poultry throughout much of the world, partially because
industrialized farming has made it very cheap for the amount of meat it
produces.
There are only two wild turkeys in the
world and both live on this
continent. One is native to the forests of North America and the other,
the ocellated turkey, is only present in the forests of the
Yucatán Peninsula. The wild turkey is a relatively large bird,
standing about three feet tall with a wingspan of up to six feet, and
weighing up to twenty pounds (the toms are considerably bigger than the
hens). Despite their weight, adults can fly up to 100 yards and usually
roost off the ground on a tree branch, both helpful strategies in
avoiding predators.
It has been estimated that 10 million
turkeys roamed North America
before European settlement but by the early 1900s, their numbers had
dropped to a scattered 30,000, mostly due to hunting and the
destruction of the forests in which they lived. Raising poults from
eggs and releasing the young birds proved a waste of time and effort as
almost none survived, but when birds from the remnant populations were
captured in rocket-propelled nets and moved to suitable forested
regions the results were quite different and the birds thrived. Wild
turkeys now live and breed in all of the lower 48 states, and their
number has risen to more than 5.5 million.
Only the male displays the ruffled
feathers, fanlike tail, bare head,
the beard of long black feathers in the middle of the breast, and the
bright red wattle and snood commonly associated with turkeys. (The
wattle hangs from the underside of the beak, while the snood hangs from
the top of its beak, both fleshy flaps of skin that evidently make him
more attractive when he is courting). Females are much more retiring
and tend to go about their business while he parades around.
Wild turkeys use vocalizations and
physical displays to communicate.
Early in the spring, each male will attempt to attract and retain a
harem of females and can be seen fanning out its tail, strutting and
"gobbling". Biologists recognize at least 15 different wild turkey
vocalizations, including the widely recognized gobble that can be heard
up to a mile away. The gobble is given primarily to attracting females
and to repel competing males. Other vocalizations are used by both
sexes to communicate a variety of messages.
Despite the fact that the wild turkey
has keen eyesight and hearing and
is quite wary, its life expectancy is thought to be no more than two or
three years. The hen lays 8 to 15 eggs in a shallow nest on the ground
and incubates them for about four weeks. The chicks are able run around
and feed themselves within 24 hours of hatching but the hen broods them
at night for the first 2 weeks and protects them for several months
after that. Turkeys are capable of breeding at about 10 months of age,
though young males are typically not successful in competing with older
males for mates during their first spring. Wild turkeys will eat just
about anything they can swallow including seeds, insects, acorns,
berries, buds, and small reptiles. Most of their food is eaten off the
ground, and they often use their feet to scratch leaves out of their
way in search of a meal. The reintroduction of the wild bird is one of
the great success stories of the Wisconsin’s wildlife management.
-------------------------------------------------
November 18, 2009: Winter Birds
While many of our familiar birds leave
us in the fall and migrate
hundreds and even thousands of miles south, there are other more
northerly species that consider our climate a great improvement over
their breeding grounds and come to spend the winter here. They begin to
arrive as the tree leaves fall, but you may not be aware of their
presence unless you are one of the many people who put out feeders that
will attract them to your yard.
Dark eyed juncos are the most numerous
and easy to identify with their
dark gray upper bodies, pale breasts, and the flash of white in their
tails as they fly. Often dubbed “snow birds”, they travel down from
Canada and now they gather around our ground feeders, eagerly gobbling
up finch seed, or fly before our cars along the roadsides in flocks of
a dozen or more, twittering in the traditional manner.
Many of the other arriving birds are
also finches of one kind or
another. The male house finch is a small bird with a fairly large beak
and a rosy red face and upper breast along with a streaked brown back
and belly. Many people see this recent introduction from our far
western states year around, especially in urban areas, but it has only
appeared here at the farm in the fall and winter. The purple finch, on
the other hand, is quite similar in appearance but breeds farther north
and is one of the fairly regular winter migrants. The male is raspberry
red on its head, breast, back and rump but does not have the streaks on
its sides that the house finch usually shows. The females of both
species are a heavily striped brown and are hard to tell apart. Both
are very fond of sunflower seeds.
Two other smaller finches sometimes
come to feeders but are more likely
to visit any birch trees you may have in your yard, hanging upside-down
at the very tips of small branches where they find catkins containing
seeds. The common redpoll is slightly larger than our goldfinch but is
heavily streaked and has a small, red spot on the top of its head and a
pink breast. Redpolls typically breed in open pine and spruce forests,
and shrubby birch and alder thickets in the Arctic. Interesting facts
about them are that they have pouches in their throats that allow them
to gather large amounts of food quickly, and also that they have been
known to tunnel into deep snow for protection. Pine siskins are
similarly streaked finches, but they have slimmer beaks and the males
usually show yellow wing-stripes and tails.
The tree sparrow is yet another finch
you may see on the ground near
your feeders. It has a rusty crown, and a black splotch in the middle
of its light, unstreaked breast. It is an insect eater that shifts its
diet to seeds and berries in the winter and comes to Wisconsin from the
tundra beyond the tree line in far north; in fact, the only time it is
spends much time in trees is when it migrates. The red-breasted
nuthatch is similar to our familiar white-breasted type but is smaller
and has red on its chest and a black eye stripe.
You will need an assortment of feeders
if you want a variety of birds,
as they prefer to feed in different ways. Some require flat
areas—either on the ground or a platform. Cardinals like this
arrangement and you may even attract evening grosbeaks. These latter
birds are much larger than the other finches and rather resemble
over-sized goldfinches in their coloring. A flock of these birds can go
through a bag of sunflower seeds in no time and although it is
interesting to observe them, you may wish they would go elsewhere to
dine.
In general, birds do not migrate south
because they cannot tolerate the
cold and snow, but because their food sources dry up. First to leave
are usually the swallows and flycatchers because the flying insects
upon which they depend disappear as the temperatures fall. Next to go
are the thrushes, wrens, and warblers that feed upon caterpillars,
worms, beetles and other such prey. When the ground is covered by a
thick carpet of snow, such food is hard to find and they must travel to
areas where the picking is easier. The finches and other species that
subsist on seeds and fruits find plenty to eat in the autumn and some
stay all winter, often moving about to take advantage of local
bounties. Now that bird watching and feeding has become such a
universal pastime across the country, some birds over-winter in areas
where it was not possible in the past.
One migrant that won’t come to your
feeders is the rough-legged hawk.
We always watch for its arrival in late fall as it sits on a wire along
the road to town. This large, soaring hawk is named for the feathers
that extend down its legs, although its most obvious field mark is its
light-colored tail that has a dark band across the bottom. One
individual or its descendent has hunted that same field for as long as
we can remember, in contrast to the snowy and great gray owls, that
come only when driven by unusual conditions up north. Watching the
activities of the birds will lighten the dreary days to come, so see
how many of these birds you can find this winter.
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November 10, 2009: Seeds: Next
Year's Flowers
I have taken advantage of the mild,
relatively dry days this past week
to get into the garden and plant some seeds. You might think this a
strange time to do this and that such an activity is doomed to failure,
but actually, it is the easiest time to acquire more perennial plants,
as many require a lengthy period of cold and wet for their seeds to
germinate. Domesticated seeds often do not need such treatment because
plant breeders through the years have routinely selected their breed
stock from plants that could do without this period of dormancy, but
the wild flowers I am planting usually will not sprout without it.
A seed is made up of a fertilized
cluster of cells (the embryo)
enclosed in a coating, usually with some stored food. Some seeds can
sprout immediately if soil temperatures and moisture conditions are
satisfactory for cell growth and division, but it is to the advantage
of most seeds to delay and this they accomplish by becoming dormant.
Delayed germination allows time for the seeds to be carried or blown to
new areas, and staggers their emergence, lessening wholesale damage
from bad weather or from being eaten.
There are two types of dormancy—that
caused by conditions outside the
embryo and that caused by conditions within the embryo itself. The
former occurs when seed coats are impermeable to water or the exchange
of gases, when seed coats are too hard to allow the embryo to expand
during germination, or when growth regulators are present in the
coverings around the embryo that must be leached out of the tissues by
rainwater or snow melt.
Internal dormancy occurs when chemical
inhibitors are present that
retard embryo growth, when the embryo needs a period of darkness or
light to begin growth, or when embryos will germinate only when the
soil temperature is warm or cool. Some plants even release their seeds
before the tissues of the embryos have fully developed, and need
further growth after they take in water over a period of time in the
ground before they can germinate.
In the wild, seed dormancy is usually
overcome by the seed spending
time in the ground through one or more winter periods and having its
seed coat softened up by frost and weathering action. By doing so, the
seed is undergoing a natural form of "cold stratification" or
pretreatment. Gardeners sometimes replicate this process by placing
seeds in a sealed plastic bag with moistened sphagnum moss (or sand or
even a damp paper towel) and then refrigerating it for several months.
The seeds can then be planted in the ground for germination.
When and how quickly seeds germinate
often depends on conditions in a
plant's original natural habitat. Many seeds will germinate at 60-75
degrees Fahrenheit, while others require temperatures just above
freezing or with alternated warmth and cold. Light is seldom important,
but some seeds, including many species found in woodlands, will not
germinate until an opening in the canopy allows sufficient light for
growth of the seedling.
Other factors vital to germination
include water and oxygen. Mature
seeds are often extremely dry and need to take in significant amounts
of water before growth can begin. The uptake of water leads to the
swelling and the breaking of the seed coat and also activates enzymes
that break down the stored food into useful chemicals. Oxygen is
required for all the chemical reactions that occur in a living organism
to maintain life, and if a seed is buried too deeply or the soil is
waterlogged, the seed can be oxygen starved. Some seeds have
impermeable coverings that prevent oxygen from entering the seed, and
germination can only take place when the seed coat is sufficiently worn
away or deteriorated.
So, what will happen to those seeds I
have so carefully planted and
labeled so that my iffy memory will not wonder what that row contains?
Many will be eaten by insects out of sight in the dirt or by birds
pecking around to see what might be hidden there. A number will be
defective for one reason or another—incomplete development, insect
damage, not fertilized, whatever. Heavy rains this fall or in the early
spring may wash some away or bury them too deeply. A snowless winter
may expose them to drying winds and extreme temperatures. Still, I am
hoping that enough will survive so that in the spring, some tiny
sprouts will emerge and eventually mature to bloom in a year or two or
in their own good time. There is magic in a seed and I never plant one
without feeling myself a partner in creation.
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November 3, 2009: Crows: In Danger?
The much-maligned crow, with its 36"
wingspan, is much the largest and
loudest of our farmyard birds and often roosts with a number of its
buddies. It is probably our most intelligent bird, having its own
language with more than 20 sounds and even able to count up to four or
five. It has been taught to mimic speech (splitting it's tongue to
allow it to talk is a cruel myth) and makes for interesting
watching. What we assume is a family group of six birds has been
visiting our lawn daily and putting on regular aerial shows. These seem
to be play, for the birds chase each other, feinting and attacking, and
sometimes tumbling and almost falling before recovering and flying off.
Perhaps you remember the stories
written by researchers on New
Caledonia Island in Melanesia who observed wild crows making tools from
leaves, and using them to extract grubs and insects from holes and
crevices. One captive crow named Betty became famous when she was
filmed making hooks from straight pieces of wire to pull up small
containers containing food. (You can see this for yourself at
(www.youtube.com/watch?v=dbwRHIuXqMU).
Then there are the California crows
that regularly drop walnuts onto
the pavement at busy intersections. The nuts are crushed by vehicles
passing over them and the birds wait for traffic to stop for a red
light before flying down to retrieve the exposed nutmeats. This
was the second time such behavior had been observed as the crows on a
university campus in Japan show the same behavior.
Now a new report has come out that
reveals another bit of information
about these surprising birds. It came from a university professor who
was beginning a study that required banding nestlings. He was able to
climb up to the nests and handle the babies without difficulty, but the
procedure frightened them and their parents. The next day when he
appeared, the crows set up a loud protest, and every time he crossed
the campus they complained again, even into the following year.
He wondered what it was that they
remembered—his clothing, size, smell,
what? He repeated the exercise, this time wearing a “tramp” mask, and
again the birds reacted. He then had students of varying age, height,
and sex, wear the mask, and the birds reacted to all of them, but not
to individuals with different masks or those without any. He then had
some wear the mask upside down and the birds were confused at first but
then tipped their heads so that they could see the mask properly and
then attacked again. The crows obviously recognized the mask face as
that of the person that frightened them, singling it out among the
crowds on the campus.
Each breeding pair of crows
establishes a home territory, averaging
about 10 acres in the city and much larger in the country, where they
build their nest and raise young. Crows usually mate for life, and crow
families tend to stick together. Older siblings may help build the
nest, feed the parent bird sitting on the eggs, feed the hatchlings, or
chase away predators such as great horned owls and red-tailed hawks.
Young crows wait at least two or more years before breeding, so family
groups can include a dozen or more individuals, and it's not unusual to
have three or more adults attending a single nest. Crows rebuild their
big, messy stick nests every year.
Wisconsin crows are partially
migratory. The breeding pair remains all
winter and appears to visit their breeding territory every day,
although they will roost and forage in other places. Non-breeders may
spend significant periods on the home territory, or may leave the area
entirely for several months. Crows have only one successful brood a
year as it takes up to four months from start until the young are
independent.
Most of us know that owls disgorge
pellets containing indigestible
remnants of their meals but many are not aware that many other birds
produce them as well. If you look under a crow roost you can often find
hundreds of large pellets consisting of small lumps of grain and gravel
held together with hair. They fall apart quickly and might be
overlooked if you didn't know what to look for.
Crows will eat anything, but at least
half of their winter diet is corn
and they spend much of their time combing fields for kernels hidden
amidst the rubble. They will also eat other grains, weed seeds
and berries, as well as whatever carrion and other animal matter they
can find. Crows are known for congregating in large numbers
to roost at night, some flocks reaching several hundred thousand birds,
but ours seem content to stay down on the farm with us.
Crows are particularly vulnerable to
the West Nile virus, and usually
die within one week of infection. Culex mosquitoes acquire the virus in
their salivary glands when they bite infected birds, and infect other
birds and occasionally mammals (including humans) when they bite again.
Their numbers are declining significantly, most notably in the
mid-Atlantic and in the Midwest states, and it would be a sad to lose
these most interesting birds.
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October 27, 2009: Owls
Throughout history people have been
fascinated by owls, sometimes
fearing them, sometimes believing them to be sources of wisdom. In the
Middle Ages in Europe, owls were thought to be witches’ messengers and
their eerie calls meant that a death was imminent or some evil was at
hand. This has been carried down in our Halloween traditions and it is
common to see their silhouettes in decorations for the holiday. Now,
they have been given somewhat better press in the very popular Harry
Potter stories where each boy in the Hogwarts wizard School had an owl
as his own private mail system. They even chose a snowy owl for the
movie part, presumably considering that its white color would make the
bird more acceptable as a pet.
Many people probably go through their
entire lives without ever seeing
an owl of any kind, even though it is a relatively common bird. The
reason, of course, is that the owl is abroad primarily after
dark. Occasionally one may fly in front of your car lights on a
back road, but during daylight hours, you are not likely to spot one as
it sits quietly in a tree close to the trunk. The Western Great Lakes
Region Owl Monitoring Program is attempting to discover just how many
of the various owl species live in Wisconsin and neighboring states,
and has organized counts for the last three or four years. Volunteers
go out to assigned areas at specified times and keep careful records of
any owl calls heard. The top three groups found were the Northern
saw-whet, the barred, and the great horned owls, with lesser numbers of
Eastern screech owls and long-eared owls.
The saw-whet is only seven or eight
inches long, but has a large head
with huge yellow eyes. It somewhat resembles a screech owl but lacks
the ear tufts of its slightly large cousin. It only calls during
the breeding season—a monotonous whistle every second or two for
several hours without a break. In contrast, the screech owl has a call
that somewhat resembles a horse’s whinny. The barred owl is much larger
and has a prominent facial disk and large brown eyes. We hear these
owls off and on much of the year as it calls "hoo, hoo, too-HOO; hoo,
hoo, too-HOO, ooo" with the last syllable dropping way down. Great
horned owls are larger still, have ear tufts and call a low-pitched
“hoo, hoo, hoo…hoo, hoo, hoo”. Long-eared owls are relatively rare and
call a repeated “who…who…who…”
Owls are instantly recognizable
because of their large, round heads and
huge, forward-facing eyes, which give them binocular vision. Their eyes
are ten times as light sensitive as those of a human but are so large
that they cannot be moved in their skulls, as there is little room for
muscles. Still, they have extremely flexible necks, allowing them to
rotate their heads as much as 270 degrees to follow a moving object.
Owls have the best hearing of all
birds. Their ears are located on the
sides of their heads and are hidden by feathers. Some species have very
obvious facial discs that guide sounds into the ear openings, and
sometimes one ear is higher than the other. When a noise is detected,
the owl is able to tell its direction because of the minute time
difference in which the sound is perceived in the left and right ear.
The owl then turns its head so the sound arrives at both ears
simultaneously, pointing directly at the prey. The so-called
"ear-tufts" on the top of the head in some species aid in camouflage
but have nothing to do with hearing.
An owl’s wide wings, lightweight body
and unusually soft, fluffy
feathers allow it to fly silently. It seizes its prey, usually a rodent
or other small mammal, and kills it with its powerful talons. If the
prey is small enough, it is swallowed whole; otherwise the food is torn
apart by the owl's strong, hooked beak. Several hours after eating, the
indigestible parts are compressed into a pellet in the gizzard where it
will remain for up to 10 hours before being regurgitated.
Owls make a very wide range of sounds
besides their common calls,
ranging from hoots to whistles, screeches, screams, and hisses. They
also make clicking noises with their beaks, and clap their wings. In
addition, many species use much body language, bobbing and weaving
their heads or ruffling their feathers. When protecting young or
defending themselves, owls may assume threatening postures, with
feathers ruffled, heads lowered, and wings spread out and pointing
down. Some species become quite aggressive when nesting, and have been
known to attack humans.
Some of the bigger owls will begin
calling in another month or two as
they begin another breeding season, and if you go out on a quiet
moonlit night to listen you may understand why the early people might
have felt shivers go down their spines. The sounds are eerie…
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October 19, 2009: Nuts and Things
The end of the growing season (the
first killing frost) seemed to come
unusually early this year, but it actually arrived right on the average
date for our area. We have been lulled by a few mild years, but
Wisconsin weather has its own agenda and all we can do is accept what
comes. The maples and aspens are displaying their brilliant colors and
in another few weeks the oaks will replace them for prime viewing, but
all too soon the landscape will be a study in grey and brown.
In addition to their leaves, many of
the trees are notable in this
season for the seeds that they produce—some of them large nuts. I had
always considered “nut” to be any seed that grew inside a hard shell,
but find that the term is much different to botanists. They tell us
that seeds are fleshy or dry fruits. Principal fleshy fruit types are
soft and pulpy such as the grape and tomato, or pulpy or leathery with
a hard pit enclosing one or more seeds like the peach, cherry, and
walnut (called “drupes”). Dry fruits are divided into those whose hard
or papery shells that split open to release the mature seed such as
legumes and many flowers with pods, and those that do not, such as
composite flowers, grains, and nuts. Therefore, botanically, a nut is a
dry fruit that contains one seed and has a thick, hard shell that does
not split open at maturity.
Certainly, the most important nut tree
in our woodlands for the
wildlife is the oak. "Across the United States, almost 100 animal
species rely on acorns as a major food source," says Gary San Julian,
professor of wildlife resources in Pennsylvania. Bears and deer eat
acorns to put on a layer of fat that sustains them through severe
winter conditions. Other animals such as squirrels, chipmunks, turkeys,
blue jays and forest mice store acorns in caches and burrows or by
burying them. Several years ago, researchers found that the
white-footed mouse consumed more than 90 percent of the acorn crop at
some of their study sites.
The acorns from the red and black oak
require two growing seasons to
mature, have a hairy lining on the inside of the shell, and have yellow
nutmeats that are very bitter. The acorns of the white oak require only
one growing season, have a smooth inner lining, and have white nutmeats
that are less bitter. The bitterness is caused by tannic acid that is
water-soluble and presumably can be removed by boiling in many changes
of water. Years ago in our more energetic days, we went through the
process, but never accomplished the pleasant nutty flavor that was
promised to make the hours of preparation worth the effort. (Native
Americans would let the crushed acorn meat soak in a fast-moving stream
for several weeks to remove the bitterness.)
The bitternut hickory also grows in
our area although it prefers wet
bottomlands. It can grow to about 70 feet and has compound leaves with
5 to 9 leaflets. The tree produces nuts after about 30 years and will
continue for a hundred years or more, although good seed crops seem to
appear only at 3- to 5-year intervals. Bitternuts have round, hard,
yellow-green husks that split along their four raised ridges, revealing
smooth, 1-inch nuts with sharp-pointed tips. They are extremely bitter
because of their high tannin content but are eaten by squirrels and
some other animals and birds.
Another much more common hickory here
is the shagbark. It may grow to a
height of 100 feet, with conspicuous shaggy bark that separates into
thick, vertical strips. Its winter buds are large and egg-shaped,
looking almost flowerlike when they open in the spring. The nuts
contain less tannin and both Native Americans and early colonists
ground them into flour or pressed them for oil. The wood is extremely
hard, heavy, and strong, and was used for wheel spokes and tool
handles, and wherever strength and resilience was required.
Black walnuts may not be nuts to the
botanist, but they certainly are
to us. Extracting the delicious meats is a tedious job, however, and
squirrels are about the only wild creatures that have teeth sharp and
strong enough to get through the hard shells. I read that ground walnut
shells are added to products used to clean jet engines, as additives to
drilling mud for oil drilling operations, as filler in dynamite, as a
nonslip agent in automobile tires, as an air-pressured propellant to
strip paints, as a filter agent for scrubbers in smokestacks, and as a
flourlike carrying agent in various insecticides. The tree is best
known for its lumber and veneer and is used for fine furniture of all
kinds, interior paneling, and gunstocks.
These tree “fruits” are unusually
plentiful this year on our trails,
and that bodes well for the winter survival of many of our wild
neighbors. Chances are most will be gathered up by one or another, or
eaten on the spot and stored as fat, but it is almost certain that a
few will escape and live to sprout in the spring. It will be many years
before any are mature enough to bear their own crops but we trust that
the forest will be here for future generations.
----------------------------------------------
October 13, 2009: Starlings and
Passenger Pigeons
When I see telephone and power lines
with hundreds—seemingly
thousands--of birds sitting tightly packed side-by-side, I am always
reminded of the stories I have heard through the years of the huge
flocks of passenger pigeons that once lived in the eastern sections of
the country.
Some estimate that there were three to
five billion of these birds in
North America when Europeans arrived, while others argue that the
species had not been common before the 1500s, their numbers growing
when European diseases killed off many Native Americans, thereby
reducing both predation and the competition for food. I have never
understood how such a huge population of a particular species could
occur, as any such excessive numbers are usually controlled by disease,
starvation, or other unexplained occurrences such as the lemmings’
sometimes disastrous migrations.
The passenger pigeon was similar to
but larger and more colorful than a
mourning dove, with a slate blue head and rump, gray back, and a wine
red breast. It fed on the nuts and seeds of chestnut, birch, oak,
maple, and pine when available but otherwise it would eat “cranberries,
strawberries, huckleberries, juniper berries, hackberries, buckwheat,
rice, wheat, oats, corn”, according to writings of John Muir. How such
numbers found sufficient food year around before large areas were
planted into crops is an unanswered question.
It was said that a single nesting site
might cover many thousands of
acres and hundreds of nests could be counted in a single tree. One
large nesting in Wisconsin was reported to cover 850 square miles, and
the number of birds involved was estimated at 136,000,000. Each
hatchling was naked and blind when born, but grew and developed
rapidly. After about fourteen days it had developed sufficiently to
take care of itself and soon fluttered to the ground to hunt for its
food.
During the late summer the flocks of
passenger pigeons frequently moved
about at random through the northern forests in search of food, but as
fall approached and the temperature dropped the flocks began their
migration to the southern wintering areas.
Because the passenger pigeon
congregated in such huge numbers, it
needed large forests and when the early settlers cut the trees for
farmland, the birds began raiding the farmers’ grain, causing serious
damage to the crops. The farmers shot many but it was not until
professional hunters began netting and shooting the birds to sell in
the city markets that their numbers began to seriously diminish.
Hundreds of thousands of passenger pigeons were killed for private
consumption and for sale on the market, where they often sold for as
little as fifty cents a dozen. Still, it was probably the loss of the
large forests that ultimately doomed the bird.
The flocks of birds that sit on our
wires in the fall can not compare
in size with those of the passenger pigeons. They are usually made up
of a mixture of blackbirds but are mostly starlings, an introduced bird
from Europe. All the European starlings in North America descended from
100 birds released in New York's Central Park in the early 1890s by a
group of Shakespeare enthusiasts who wanted America to have all the
birds he mentioned in his writings. Today, more than 200 million
European starlings range from Alaska to Mexico, and many people
consider them pests.
The starling is a chunky
blackbird-sized bird, with a short tail and
long, slender beak. In flight its wings are short and pointed, making
it look something like a small, four-pointed star (presumably giving it
its name). Although it looks black at a distance, it is purplish-green
iridescent with a yellow beak in the summer, and brown covered in
bright white spots in the fall after molting.
A starling is boisterous and loud, and
often sits on wires or high in
trees with its buddies making a constant stream of rattles, whirrs, and
whistles. It often includes the birdcalls of other species and sounds
from its surroundings into its vocalizations, and sometimes includes
car alarms, and even human words.
Starlings will eat nearly anything,
but they focus on insects and other
invertebrates when they’re available and so should be welcome visitors
to our yards. The problem is they also eat fruits such as wild and
cultivated cherries and blackberries, and gather in considerable
numbers at feedlots where they feast on grain and livestock feed.
The birds have often been given a bum
rap and accused of replacing
native bird populations but according to the Cornell Laboratory of
Ornithology, a study in 2003 found few actual effects on populations of
27 native species. Only sapsuckers showed any decline due to starlings
while other species appeared to be holding their own against them. At
any rate, starlings are here to stay and since their population seems
to be stable, we might as well enjoy them.
---------------------------------------------------------
October 6, 2009: Fairy Doodles:
Flying Squirrels
If you live in a wooded area, take a
flashlight out to your bird
feeders after dark and see if some fairy diddles are visiting, a name
commonly used in some localities for flying squirrels. These small
animals are only active at night, and so are not often seen, even
though in some areas, they may actually outnumber the familiar gray
squirrels. Their numbers in good habitat may approach five squirrels
per acre and each is thought to have a range of one to five acres.
I am told that if you hold up a baby
flying squirrel by its tail even
before its eyes have opened, its four legs will automatically extend
out to its sides, spreading the folds of skin that are attached from
the wrists on the fore feet to the ankles on the hind feet. These extra
flaps of skin are what make flying squirrels unique, as even though
they can’t really fly, they can make spectacular glides.
The adult squirrel climbs high on the
trunk of a tall tree and then
turns and hangs there moving its head up and down and back and forth,
possibly judging the distance. It then launches itself with all four
legs extended from the body, stretching the flying membranes. The
animal can steer around branches or other obstacles using its long flat
tail and by varying the tension on the skin membrane. Just before
landing on another tree trunk, it drops its tail and lifts its feet,
and lands very lightly, hind feet first, and at once scurries around to
the other side to thwart any watching predator. Glides can extend for
more than 50 yards, but are usually much shorter.
There are two species of flying
squirrel in Wisconsin--the northern and
the southern. The northern flying squirrel can be found in heavily
wooded areas of mixed conifers and deciduous trees, and prefers moist
forests with many fallen, decaying and mossy logs. This is because a
large portion of its diet is made up of mushrooms, truffles, and
lichens that thrive in such locations; in fact, these flying squirrels
are thought to be important to forest regeneration because they
disperse spores of fungi in their feces upon which many trees are
dependent. The squirrels also eat many nuts, tree sap, insects,
carrion, bird eggs and nestlings, buds and flowers.
Although the northern flying squirrel
is larger, the southern variety
is more aggressive and tends to be dominant where their ranges overlap.
This is the species that is found in our woods and is usually only
about nine inches long including the tail, and weighs about three
ounces. Its fur is soft, silky and grayish to brownish in color, with
creamy white underparts, and it has very large dark eyes, long
whiskers, and a furred, broad tail that serves as a rudder and
stabilizer during glides.
Acorns and hickory nuts make up the
bulk of the diet of southern flying
squirrels but they also eat seeds, fruits, berries, and mushrooms, as
well as insects, bird eggs and nestlings, small nestling mammals, and
carrion. Nutshells upon which flying squirrels have been chewing
usually show a characteristic pattern as the squirrels cut a single
fairly smooth circular or oval opening on one side or end. Deer mice
and white-footed mice make similar holes, but typically cut two to four
holes and other tree squirrels usually chew the shells into fragments.
Southern flying squirrels breed in
February and March, and a litter of
three or four young is born in about 40 days. Newborns are tiny, naked
and helpless, with eyes and ears closed. They weigh less than a
quarter-ounce each, and the gliding membrane is already visible as a
transparent fold of skin. The ears open at about three weeks of age,
and a week later the eyes open. The young are weaned at six to eight
weeks and are capable of gliding soon after. Males typically leave the
nest before the young are born and do not assist in caring for the
young, but the females are devoted mothers and will defend their broods
rigorously and move them to new nests if disturbed or infested with
parasites. The young typically remain with their mother until the birth
of the next litter.
As the day lengths become shorter, a
southern flying squirrel may store
up to several hundred nuts in a good year--hopefully sufficient to
carry it through the winter. Although it is active in all seasons, the
southern flying squirrel may remain in its nest in very cold weather
and will enter torpor in times of extreme cold or food scarcity. This
is not as deep as true hibernation, but the animal’s body temperature
can drop to 75°F and it may take up to an hour to wake.
Our Montana daughter reminds me she
camped out back in the woods when
she was a teenager just to see a flying squirrel, and was thrilled to
watch one glide from tree to tree. We even saw one on the stage at
American Players Theater one moonlit evening, and the engaging creature
drew more attention than the actors on the stage as it scampered up the
rough boards. These social animals congregate in hollow nest trees
during daylight hours all year long and a tap on such a tree may send
half a dozen gliding to safety. Call me if you see one. I’d like to
hear about it.
-------------------------------------------------
September 29, 2009: A Wolf Bird; The
Peregrine
The peregrine falcon might be called
the wolf of the bird world as it
is an impressive predator. It is a large, crow-sized bird, with a
blue-gray back, barred white belly, and a black head and "moustache",
and can be distinguished from a hawk by its long pointed wings that can
stretch to 3 ½ feet in length. Its diet consists almost
exclusively of medium-sized birds, although it will occasionally hunt
small mammals, small reptiles or even insects. Both the English and
scientific names of this species mean "narrow-winged wanderer",
referring to the migratory habits of the more northerly populations. It
is the world's most widespread bird of prey as it can be found nearly
everywhere on Earth.
The peregrine historically nested on a
cliff edges, but today it can
also be found on tall buildings, bridges, and smokestacks at power
plants. In March, the female lays three to four eggs directly on the
surface of the nest site, and incubates them for about four weeks. The
life span in the wild is up to fifteen years but more than half die in
their first year. A pair mates for life and returns to the same nesting
spot every year. The courtship flight includes a mix of aerial
acrobatics, spirals, and steep dives, and the male often passes prey it
has caught to the female in mid-air while the she actually flies
upside-down to receive the food from the male's talons.
The peregrine falcon is often thought
to be the fastest animal on the
planet in its hunting dive, which involves climbing to a great height
and then diving steeply at speeds commonly thought to be over 200 miles
per hour. Once prey is spotted, it folds back its wings, tucks in its
feet, and narrows its tail. The air pressure from a 200 mph dive could
possibly damage a bird's lungs, but small bony tubercles in a falcon's
nostrils divert the shock waves of the air entering the nostrils
enabling the bird to breathe by reducing the change in air pressure. To
protect their eyes, the falcons have transparent third eyelids that
spread tears and keep out debris. The falcon strikes prey on its wing
with a clenched foot to disable it, and then turns to catch it in
mid-air. If it is too heavy to carry, the peregrine will drop to the
ground, kill it by biting into its neck and pluck it and eat it on the
spot.
In the 1930s and 1940s, there were
approximately 500 breeding pairs of
peregrine falcons in the eastern U.S. and approximately 1000 in the
western U.S. and Mexico but increasing use of DDT and other pesticides
caused the population to crash. The nests along the Wisconsin River
were abandoned by 1957, those along Niagara Escarpment in Door County
by 1958, and the 14 nests along the Mississippi River by 1964. It was
listed as a federally endangered species in 1970 and a Wisconsin
endangered species in 1975.Wisconsin banned the use of DDT in 1971
followed by the federal government ban in 1972, and reproductive rates
of the falcons began to improve, but it was felt that reintroduction
was needed in areas where the birds had completely disappeared. The
Wisconsin Peregrine Falcon recovery program began in 1987 with the
release of 14 captive-produced young peregrines in Milwaukee followed
by releases in Madison, La Crosse, Racine, and Pleasant Prairie.
Today, there are more than 2,000
nesting pairs in the United States,
(far exceeding the program's goal of 631 nesting pairs), more than 400
pairs in Canada, and an estimated 170 pairs in Mexico, and it was
removed from the U.S. Endangered Species list in 1999. As of 2006, the
Wisconsin reintroduction program had established 27 territorial pairs
and fledged 435 young, and last year there were six active nests on
buildings, six on smokestacks at power plants, and three on cliffs
overlooking the Mississippi River. The big news at Madison this summer
was that a peregrine chick hatched in a nesting box at the Madison Gas
and Electric plant. A MG&E employee and his son built the box and
placed it at the plant in the late nineties, but no falcons had ever
visited the site until this year. The male of this pair had previously
been banded near a Milwaukee power plant, and it is thought that
peregrines like power plant locations because of their height, and the
abundance of pigeons as prey.
The peregrine falcon feeds mostly on
medium sized birds such as doves,
waterfowl, songbirds, waders and pigeons, but it is thought that it may
prey upon between 1,500 and 2,000 bird species around the world. In
North America, they have been observed attacking prey that has varied
in size from tiny hummingbirds to a sandhill crane. Like some other
projects (such as protecting the wolf) in which we have involved
ourselves, we may find we have encouraged a species that might
ultimately give us problems we never envisioned.
-----------------------------------------------------------
September 22, 2009: A Wisconsin Gem
We climbed aboard a unique train last
Saturday for a short ride into
one of Wisconsin’s gems—the Tiffany Wildlife Area. The state has
one hundred of these wetland areas that have been designated as “gems”,
and we were eager to see what was special about this one.
The occasion was a field trip
sponsored by the Wisconsin Wetlands
Association, a statewide non-profit group established in 1969 to
promote the protection of the state's wetlands. It organizes some
fifteen excursions throughout the state during the summer months that
focus on one or more of these gems and we had registered for this
particular one after seeing it high-lighted on Wisconsin Public
Television’s In Wisconsin.
Tiffany State Wildlife Area is located
just north of the delta formed
by the Chippewa River where it joins the Mississippi and includes some
13000 acres of bottomland forest and wet prairie. It runs generally
north to south until it connects with the Upper Mississippi River
National Wildlife Refuge and these two parcels and nearby rivers
represent the most extensive river delta system in the Upper Midwest.
It was named for one former owner, H. O. Tiffany, who purchased 8000
acres of the land in the early 1900s for logging and cattle grazing
after earlier efforts to drain it for cropland proved to be
impractical. Then, in the 1930s when the lock and dam system on the
Mississippi raised the water table even higher, he logged what he could
and then sold his land to the State of Wisconsin in 1946. Since
then, additional land has been purchased by the state and it has been
managed for wildlife habitat.
The railroad line that runs through
the wildlife area along the river
was built in 1882 to connect Wabasha, Minnesota to Eau Claire
Wisconsin, using a pontoon system to float over the Mississippi River.
Trains hauled freight until 1975, when a derailment ended its
usefulness and it was abandoned. The rail bed then was purchased by
Xcel Energy as part of a plan to transport coal to a future steam
generating plant north of Durand, but nothing came of that. Then, in
1995, 14 miles of the track was leased by a group of private rail fans,
and the Chippewa Valley Motor Car Association was formed. Its members
cleared and repaired the tracks and rail bed and acquired several A-4
Fairmont motor cars, small inspection vehicles powered by two-stroke
engines that were used by the railroads. They then installed 4-cylinder
Ford engines in two of the A-4's and now use them at the head and rear
of a number of gang cars, transporting up to one hundred sightseers to
the end of the track and back.
Our group climbed aboard the open
cars, eight riders to a unit, and
bumped along at up to 15 miles an hour (although usually much slower).
We crossed several small wooden trestle bridges and one steel bridge
and marveled at all the work it must have taken to create a raised rail
bed through all the swampland 130 years ago. We passed through
bottomland forest made up of huge old silver maples, aspen, oak, river
birch, ash, and cottonwood, virtually impenetrable wetlands sprinkled
with varying sized ponds, large meadows, and along a section of the
Chippewa river. We were told that the prairie sections were once far
more widespread than they are today as the Native Americans repeatedly
burned them to keep the areas open for wildlife. The state still burns
every five years and makes an effort to control trees and brush that
might overwhelm less robust plants.
The trip was led by several
naturalists and biologists from the
Wisconsin Department of Natural Resources and University of
Wisconsin-Eau Claire and they each talked about their
specialties. We left the train for two hikes out into prairie
segments—one into an extensive area carpeted with little blue stem
prairie grass. Along its edge grew numerous closed (or bottle) gentian
wildflowers and small white asters that our flower expert identified as
Ontario asters. The blue blossoms of bottle gentian are in clusters of
up to a half dozen elongated buds that never open, and can be found
only in wet meadows. I also saw lots of culver root that was now in
seed after displaying its slender spikes packed with small white
flowers earlier in the season.
Overhead circled several
red-shouldered hawks, and two bald eagles--an
adult showing its white head and tail, and the other an immature that
was a mottled black all over. A vulture also paid a visit and a flock
of bluebirds flew about in the bushes some distance away. Otherwise,
the place seemed almost devoid of birds, but I’m sure that was only
because they were taking a mid-day siesta before renewing activities
later in the afternoon.
We ate our picnic lunches by the side
of the tracks and listened to the
stories of the organizations involved in the state’s wetlands and their
inhabitants. They told us that a number of endangered and threatened
species live there including the massassaga (a swamp rattlesnake), the
Blandings turtle, red-shouldered hawk, great egret, and bald eagle but
it was not the time of day for wildlife watching and we had to be
content with talk. It was an interesting day, however, and a unique
field trip you might want to experience for yourself another year.
September 15, 2009: Birding in
Duluth
We were caravanning with a group of
birders along the north shore of
Lake Superior last weekend when the lead car suddenly pulled over to
the side of the road and stopped. The rest of us followed its example,
jumped from our vehicles and grabbed our binoculars. All we saw of the
black-backed three-toed woodpecker (I am not making that up!) was a
rapidly departing shape disappearing into the distance. Our leader
explained that the bird had flown across the road in front of him,
landed briefly in a small tree where he made the identification, and
then flew off. I’m afraid that was the high point of our birding trip
to Duluth.
Migrating birds, that spent the summer
nesting as far north as the
Arctic and heading south to destinations as far as South America, seem
to be reluctant to cross large bodies of water, and when they reach
Lake Superior, they follow the lakeshore and are often concentrated in
impressive numbers on the bluffs overlooking Duluth. On days with
northwest winds, hundred to thousands of birds of all types can
sometimes be seen from the ridge above the city. Our main interest was
on raptors, however, and we were told that the action begins in
mid-August with American kestrels, sharp-shinned hawks and broad-winged
hawks, and continues into December with the last of the red-tailed and
rough-legged hawks, northern goshawks and eagles.
Before 1950, the only people there who
paid much attention to these
large birds were local hunters who used the birds for target practice.
Then the Duluth Bird Club (now the Duluth Audubon Society) took up the
fight against the illegal shooting and organized the first hawk watch
in 1951. Their efforts resulted in a greater awareness of the
importance of protecting the birds, and in 1972, the Society with help
from The Nature Conservancy, donated funds to the City of Duluth to
purchase the highest part of the ridge above the city. Two hundred
adjacent acres were added in 1973, and now the Hawk Ridge Bird
Observatory manages the 315 acres as a nature reserve. It is known as
one of the major sites for observation of raptor migration, and
thousands of visitors come from all 50 states and from over 40 foreign
countries. In September, the organization hosts a special weekend,
offering field trips with professional birders as guides, bird banding,
lectures, and other activities.
Duluth, Minnesota and Superior,
Wisconsin are located above the
freshwater estuary formed by the St. Louis River, where it flows into
western end of Lake Superior. The river is 179 miles in length and the
river's watershed is an impressive 3634 square miles in area. Duluth,
itself, is a city on a hillside cut deeply with numerous small streams
with wooded edges. Its elevation rises from around 600 feet at the
lakeshore to more than 1400 feet at the ridge, and we found it a bit of
a challenge to find our way around. It has a population of more than
300,000 people, but we were quite surprised to be shown the scat of a
bear in the back yard of my niece’s home in a central part of the city.
She also has trouble with deer feasting on her garden vegetables, and
says that those wooded areas that are spread across the city host a
great variety of wildlife.
The weekend was far from ideal for
seeing migrating birds. The
temperature reached 83 degrees F each day and what wind there was came
from the south. We made our way up to the ridge top activities, but
little was going on. The only close sighting was a merlin (a small
falcon we have seldom seen here in the southern part of the state) that
made a casual fly-by of the two decoy owls that adorned two poles. It
was obviously unimpressed and went about its business elsewhere,
leaving us and the rest of the gathered visitors scanning the mostly
empty blue sky.
Our two field trips were slightly more
successful—not that we saw many
raptors, but we did get glimpses and sometimes good sightings of a
variety of warblers. Only a few of these tiny birds nest in southern
Wisconsin while the great majority raise their young up in Canada and
must make their way a thousand miles and more to Central and South
America. We searched along the northern shorelines in the brush and
overhanging trees and then out onto Park Point. This is a
seven-mile-long sand bar that spans the estuary and is said to be the
longest freshwater sand bar in the world. A road goes much of its
length after crossing an interesting lift bridge and ends at a park
that usually provides excellent birding. Not this particular weekend
however, and our guide commented that should any of us ever decide to
lead birding expeditions, he would advise not to agree to do one during
migration times as all activity is so dependent upon the weather.
The maples, walnuts, and aspens on the
drive north were beginning their
fall display and there were splashes of crimson, and gold among the
green conifers all along the highway. And the days—so unsatisfactory
for bird watching—were gorgeous for just enjoying the out-of-doors.
What a beautiful state we live in!
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September 8, 2009: A Hornworm?
Take a flashlight out into your flower
garden on a warm summer’s eve
and you may catch a glimpse of one of our most interesting flying
insects. The eyes of a white-lined sphinx moth will shine brightly
whenever it crosses the flashlight’s beam and you can follow it as it
visits flower after flower, poking its long tube-like proboscis deep
into its center. This is probably the most commonly seen of the
"hummingbird moths", and is easily identified by the white band across
its wings. Its larvae feed on a variety of plants, but portulaca (our
garden weed purslane is in this family), primrose, and wild grape are
preferred.
There are some thirty species of
large, heavy-bodied moths with narrow
front wings that live in Wisconsin and all are referred to by four very
different names. “Hummingbird moth” comes from the adult form and
describes its ability to fly forward, backward, and sideways with very
rapid wing beats. Two names refer to the larval stage—“hornworm” is
used because almost all have a spine on the tail when they are
caterpillars, and “sphinx moth”, because when alarmed, the larvae rear
up their heads in a threatening sphinx-like posture. I don’t understand
the fourth name—“hawk moth”—unless that, too, is reference to its
ability to hover. It certainly is not predatory or fierce or any of the
other characteristics we usually connect with a hawk.
Despite the eye shine of the
white-lined sphinx, most other moths go to
great lengths to avoid such an attention-grabber. The outer surfaces of
their corneal lenses are covered with a regular pattern of tiny cones
that evidently reduce light reflection. These unique structures seem to
help moths evade detection by predators that might see any eye shine,
and also maximize light capture for seeing in the dark. Engineers are
studying these moth eyes in an effort to improve anti-reflective
coatings for commercial products.
The largest of our Wisconsin
hummingbird moths are commonly known by
the inelegant names of tomato and tobacco hornworms. These are abundant
but seldom seen as they fly after dark, in contrast to the white-lined
sphinx that comes out at dusk. Adults of both species are large, stout
moths with a wingspread of up to 5 inches. The tomato hornworm moth is
mainly gray in color and there are usually 5 pairs of yellow spots on
its abdomen while the tobacco hornworm moth is mostly brown with 6
pairs of spots.
The caterpillars of both these moths
have green bodies with white
markings, reach a length of at least 3 inches at maturity and have
stupendous appetites. A heavy infestation in a vegetable garden may
strip some of the tomato plants of their leaves and make holes in the
fruit as well. Still, few grow to maturity because predatory insects
such as lady beetles and green lacewings attack the caterpillars when
they are small, and braconid wasps lay their eggs on them as they grow
larger. These hatch into larvae that burrow into the caterpillars to
feed, and then pupate as white projections attached to their bodies,
eventually killing them.
Although they have adapted to feasting
upon our crops, the caterpillars
of the tomato and tobacco moths originally fed primarily on horse
nettle, nightshade, and jimsonweed. This latter plant is of interest
because its leaves, stem, root and fruits contain a number of
alkaloids, the most potent of which are atropine, hyoscyamine and
scopolamine. These chemicals are known for affecting the human central
nervous systems, but the adult moths seem to find them highly
attractive. They have been observed to hover around the flower buds
presumably waiting for the blossoms to pop open, and then appear to
become intoxicated upon feeding, as they fly erratically, bump into
plants and even fall down to the ground.
The full-grown hornworm larva migrates
from its host plant and digs
down a few inches into loose soil. It splits its skin a final time,
creating a small chamber of packed dirt as it gyrates in the process.
The pupa is typically brown, two inches or more in length, and many
have a pronounced "snout" off the head end. First generation adults
emerge in early July and second generation larvae are present from
early August to early October and over winter as pupae.
Those of you who read my columns
regularly may have surmised that I am
a great fan of all the moth species. I have bemoaned the fact that no
tomato hornworms have visited my garden in years and even went so far
last year as to release a mature caterpillar from a neighbor’s patch
onto one of my tomato plants. Well, I am now satisfied. A week ago, I
noticed the top branches of my six-foot caged plants were noticeably
shorter and when we looked through the leaves, counted at least a dozen
large caterpillars. They actually did no more damage than I usually do
in pruning off new growth as the season ends, and all have now
disappeared, presumably down into the dirt to pupate. If they survive
the winter and the rototiller, perhaps next summer we will have some of
these beautiful moths flying about.
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September 1, 2009: Going bats
There are close to 1000 different
kinds of bats worldwide; in fact,
they make up about 20 percent of all the mammal species. They range
from one that is about the size of a bumblebee to flying foxes with
nearly six-foot wingspans. All have been divided into two categories --
megabats and microbats. The larger megabats generally have big eyes and
small ears, fox-like faces, live in the tropics, and feed on fruit,
nectar, or pollen. Microbats are smaller, are insect eaters, and rely
more on their ears than their eyes to find food.
Microbats feed at night using
echolocation -- the ability to find
objects based on how they reflect sound. As a bat flies about, it
generates ultrasound waves in its large, bony larynx, and sends them
out through its open mouth. When searching it produces ten to twenty
pulses per second but if it detects something, it increases the rate to
as high as 200 per second. The echoes it receives back direct it to its
target and allow it to avoid obstacles in its path. Almost all of these
pulses are above the frequency range of the human ear.
Many species of bats live in huge
colonies of thousands, while others
are solitary. In cold climates, as winter approaches, they must either
migrate to warmer areas or hibernate. When bats hibernate, the body
temperature drops, the breathing slows to once or twice a minute, and
the heart rate drops from a normal rate of 200 to about 20 beats per
minute. In this state they are very vulnerable and sometimes die if
disturbed. Bats can live twenty to thirty years if they survive the
first few weeks when mortality is high.
There are seven species of microbats
(and no megabats) in Wisconsin,
and although most are quite numerous, only the little brown and big
brown bats are commonly seen as the others live in the woods. The
little brown bat has a wingspan of about ten inches and feeds mostly on
small, flying insects. It breeds in the fall and then flies to the
nearest suitable cave or abandoned mine to hibernate, sometimes
hundreds of miles from its summer territory. Over the winter the male's
sperm is stored inside the female's body, and the infant is conceived
in spring.
When temperatures allow, the female
little brown bats go to nursery
colonies that are often located in the attics of warm buildings where
there is high humidity. One infant is born each year, and it will cling
to its mother as she flies, nursing almost continuously. At three
weeks, it learns to fly and by four weeks, it will reach adult size.
The big brown bat, with a wingspan of about twelve inches, roosts in
colonies in tree hollows, wall spaces, and buildings. It often has
twins and is the only one that commonly over-winters in walls and
attics and can survive a body temperature of the only slightly above
freezing in hibernation.
Most of the other species are also
abundant, but in general there have
been fewer studies about them and so less is known about them. The
northern long-eared bat and the red bat are similar in size to the
little brown but the first has prominent ears and the second has
red-orange fur. They both live in the woods, and when cold weather
arrives, they migrate to central and southern states where they
hibernate in rock crevices and tree hollows.
The hoary bat is one of the largest
microbats in the United States (it
may have a wingspan of 16”) and has dark yellowish fur with white tips
giving it a frosted appearance. Pairs come together only to mate and
during their long seasonal migrations to and from warm winter habitats
in sub-tropical or tropical America.
The eastern pipistrelle is Wisconsin's
smallest bat with a body length
of less than three inches and a wingspan rarely exceeding seven inches.
It emerges earlier in the evening than most other bats and has a
relatively slow erratic flight pattern and is sometimes mistaken for a
moth. It winters in a cave or other frost-free spot, and because
pipistrelles are quite sensitive to cold, they are among the first bats
to begin hibernation in the fall and last to leave in spring.
I have always assumed that the species
we see here at the farm is the
big brown bat as it seems to have made its home in our attic year
round, but it is difficult to identify a bat when it is only seen
flying overhead at dusk. Whatever they are, we like having them around
for they patrol the farmyard every evening, feasting on the mosquitoes
and other flying insects. A little brown bat is said to eat up to 900
small insects in an hour, and it has been estimated that an average
colony may consume 500,000 insects or more each night. If only the
Japanese beetles flew after dark…
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August 25, 2009: A Climbing Fox
There are two species of fox in our
area—the red and the gray. The red
fox is more commonly seen, partly because there are more of them, and
partly because it tends to hunt in open fields and along roads. The
gray fox is more reclusive and tends to stay in rough country with lots
of edges, timbered hills, and away from people. Both do most of their
hunting between dusk and dawn and rest during the day.
The red fox looks a lot bigger than it
is because of its thick fur, but
typically weighs only about 12 pounds. It usually has a rufous coat
(although other colors from blond to black are sometimes seen), a long
bushy tail, long black legs, and always has a white tip on its tail.
The smaller gray is typically several pounds lighter, has shorter legs,
mostly gray grizzled fur, and a black tip on its tail.
Immigrant Englishmen in the 17th
century missed the fox hunting of
their homeland and introduced the European red fox to the east coast,
where it thrived and spread westward until it is now present across
much of the continent. All the red foxes we see are the offspring of
these imports, although it is believed that some may have crossbred
with a red species native to Canada and Alaska.
Foxes have large, upright ears and
excellent hearing. It is said that a
fox can hear a mouse squeak from 150 feet away and can pinpoint its
location. It will creep up on its prey, crouching low to the ground,
and then pounce with its forefeet. Foxes seem to prefer rabbits, but
also feed heavily on mice and voles. They also eat fruit, berries and
insects when they are available, as well as almost anything else they
can catch or salvage.
A red fox family has a hunting
territory of about 150-400 acres, but
where there are a number of cultivated fields, one family might need up
to two to three square miles. The home range size of the gray fox
varies tremendously from 30-750 acres, also depending upon the quality
and quantity of food and shelter. When they have pups to feed they
usually stay within a mile of the den but at other times they may
travel up to nine miles in a single night. When resting during the
daylight hours, they spend their time curled up in forests, ravines or
woodlots, wrapping themselves in their long bushy tails.
Both red and gray foxes are
monogamous. A red fox pair breeds in
January and February and often chooses an old woodchuck burrow or
hollow log for a den, lining it with a soft nest of leaves and grass
for their 4-5 pups. The gray fox breeds between mid-February and late
March and prefers a rock outcropping on a timbered hillside if one is
available. Gray pups are born in April to mid-May, each weighing about
3 ounces and blind and naked. Most dens are situated on east, southeast
and south facing slopes to take advantage of the warmth from the sun.
Grays use their dens year-round while the reds use them only when their
pups are born.
The pups’ eyes open around eight days
after birth, and fuzzy fur begins
to cover their bodies. When they are about a month old, the pups begin
to come out of the den to play. The adults bring food to them there,
chewing and then regurgitating prey at first and then bringing it whole
as the pups grow. The outside of a fox den often has an unpleasant odor
not unlike that of skunk even though the parents carry away the pups’
droppings and foods that spoil. By three months, the young are
following their parents away from the den, and by 4 months they are
hunting on their own, although they often stay in family groups until
fall.
A unique fact about gray foxes is that
they can and often do climb
trees. They climb like cats, using their strong claws to grasp the
trunk and pushing upward with their hind feet. The fox climbs
headfirst, and can descend either headfirst or tail-first and can jump
from limb to limb almost like a squirrel. It may climb to escape
predators, to hunt prey like birds and squirrels, to ambush prey from
above, to forage for fruits, nuts and eggs, and apparently, simply for
fun. They have been seen to nap on sunny branches, and hide and sleep
in hawk and owl nests. Occasionally, they will even use hollow trees 20
feet or more above ground as dens in which to raise a litter.
There are thought to be about 60,000
to 70,000 red foxes in Wisconsin
and perhaps 12,000 gray foxes, most of which are in the Driftless Area
and the southern kettle moraine. More than half die each year, mostly
from hunting and trapping, but the populations of both are thought to
be relatively stable. The gray fox will undoubtedly never be as common
in Wisconsin as the red fox, as it is more dependent on deciduous
forests and rugged terrain.
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August 18, 2009: Beetle Battle
I have felt rather smug this past
month as I patrolled both my farmyard
and wild gardens with a bucket of soapy water. My prey were the
Japanese beetles that were scattered here and there, feasting upon my
precious plants, and it was relatively easy to knock them off into the
container where they soon drowned—the soap in the water removing their
protective waxy coating. I have had relatively few of these pests in
past years compared to many of you in urban areas, but now that they
have arrived in some numbers I was determined to hold them in check.
This past week, with the tardy arrival of summer, I received a reality
check. Hundreds of the beetles have appeared, and we are having to
patrol the area several times a day to collect them—hopefully before
they can lay the eggs that will be next year’s generation.
The Japanese beetle is probably the
most devastating pest of urban
landscape plants in the eastern United States. It was first discovered
in 1916, after being accidentally introduced into New Jersey from Japan
where it causes only minor damage. The beetle thrived as it found a
favorable climate, large areas of grass for developing grubs, hundreds
of species of plants on which adults could feed, and no effective
natural enemies. Now it has steadily expanded its range north to
Ontario and Minnesota, west to Iowa and Missouri, and south to Georgia
and Alabama.
The adult beetle is 7/16-inch long,
metallic green with copper-brown
wing covers, and has a row of white tufts of hair projecting from under
the wing covers on each side of the body. It has no problem finding
food as it feeds on the leaves, flowers, and even fruit of about 300
species of plants. A single beetle does not eat much, but they usually
feed in groups, starting at the top of a plant and working downward and
can do severe damage. The beetles are most active on warm, sunny days,
and prefer plants that are in direct sunlight.
The Japanese beetle begins its life
underground as a tiny white grub,
usually in a grassy area, and it feeds on the roots it finds growing
all around it, eventually growing to about an inch long. When the soil
cools in the fall, the grub will begin to move deeper and most pass the
winter around 6 inches below the surface. When soil temperature warms
again in the spring, they resume feeding for another 4-6 weeks, and
then change into pupae. In late June and into July, the beetles emerge
and crawl to the surface where they find food and mates. The female
then burrows 2 to 3 inches into the soil and lays about 50 eggs.
Females are attracted to moist, grassy areas and irrigated lawns often
have high grub populations, especially during dry summers. Individual
beetles live about 30 to 45 days.
Gardeners with large infestations
sometimes invest in commercial beetle
traps that use either the scent of virgin female beetles or the odor of
a sweet-smelling food. Both of these are highly effective—so much so
that they often attract far more beetles than the traps can handle and
so do more harm than good in an area. I will attest that hand picking
is a real chore but is probably far more effective.
A couple other imported beetles have
also made the news in recent
years. The Asian long-horned beetle is about an inch and a half long,
glossy black with irregular white spots, and has long black and white
antennae. The adults emerge in late summer to feed on several species
of hardwood trees, and are particularly fond of maples. Mated females
chew up to ninety individual shallow holes into the host tree's bark
and lay an egg in each. The eggs hatch into white, caterpillar-like
larvae that tunnel beneath the tree bark and feed on the inner tissue.
They spend the winter inside the tree, mature into pupae, and by the
next summer chew their way out of the tree as adults. Repeated
infestations eventually kill the tree, and the insects are often spread
in firewood.
The emerald ash borer is similar in
that its larval stage also damages
trees, although at this point it seems restricted to ash trees. Adults
are dark metallic green in color, about one-half inch long, and begin
emerging in late May. Peak emergence occurs in mid-June and egg laying
takes place soon after. Infested trees exhibit top-down dieback, with a
third to a half of their branches dying the first year and the
remaining canopy dying the following year.
Your chances of finding either of
those two beetle species are slim
here in southwestern Wisconsin at this time, but all of us have become
well acquainted with another introduced beetle—the Asian lady beetle.
At least this insect is only a nuisance and not only does little harm
but is actually beneficial as it eats aphids and other soft-bodied
pests. Regardless of their good or bad points, such beetles are
probably here to stay, but I’ll continue trying to hold off the
inevitable in my garden.
August 11, 2009: Cranes and More
Cranes
When you see all the flocks of
sandhill cranes gathered by the dozens
in harvested fields, it is difficult to believe that not too many years
ago, they were thought to be endangered. Their recovery from near
extinction has been a great success story, as only a century ago there
were but twenty-five known breeding pairs in the state and the
situation wasn't much better elsewhere in the country. Hunting
pressure and habitat loss were blamed for the situation but it is now
believed that other factors might also have been in play. Whatever the
reason, the population has now rebounded and prime nesting habitat is
filled to capacity, with the adjacent lands quickly saturating as well.
The birds are also acclimating to their human neighbors and are nesting
in areas where they never would have been found in the past, and in
future years we may find cranes becoming as familiar a sight as have
the Canadian geese.
An interesting fact about the sandhill
crane is that it has existed
virtually unchanged for longer that any other living bird. There is a
fossil 2.5 million years old that is structurally identical to the
modern sandhill, and a 10-million-year-old fossil from Nebraska that is
somewhat similar, although a different genus and believed to be a
prehistoric relative.
There are fifteen species of cranes in
the world and eleven of them are
endangered or threatened. Sandhills are one of two species found in
North America, the other being the whooping crane. The sandhill is a
large bird, often standing four feet tall and with a wingspan of seven
feet. Both males and females have gray plumage, yellow eyes, black
bills, legs and feet, and bright red patches on the crests of their
bald heads. In the spring, they daub their feathers with mud, possibly
to camouflage themselves while on the nest.
Perhaps their most interesting
characteristic is one the sandhills
share with of all the other crane species—a unique windpipe. It may be
5 feet long, looping around itself in the chest next to the breastbone
something like a French horn, and allowing the bird to produce its
strange, haunting call. Most of the trumpeting is done by the
leader of each individual flock and can be heard for as far as two
miles.
There are six sub-species of sandhill
crane, and the birds we see are
probably of the greater sandhill race that nests in Wisconsin,
Michigan, Minnesota, and Ontario. These gather in family groups in safe
staging areas in the fall—our biggest three being the Sandhill Wildlife
Area near Babcock, Crex Meadows in the far northwestern part of the
state, and the Horicon Marsh. The fact that the Wisconsin River
contains many large sandbars for safe resting is probably the reason
for the large concentrations that also stage in our area. As the
weather worsens and the water here freezes, most of these birds will
travel on into northeastern Indiana to the Jasper-Pulaski State
Wildlife Area where they will remain until winter catches up to them.
Then they will continue on to southern Georgia and Florida.
The cranes return to Wisconsin early
in the spring and immediately set
up housekeeping. Each selects a mate by the time it is four years old
and the pair will stay together as long as both live, in some cases 25
to 30 years. Both established pairs and unattached singles participate
in a unique courtship ritual. They perform a series of dances,
alternately bowing and leaping into the air with wings stretched out as
they circle each other. While they dance, the males give out with
single loud calls, and these are often joined by a female’s two-note
answer. After they mate, each pair creates a bulky nest made of piles
of grasses and other plants heaped in a grassy area near or floating on
open water.
The female will lay one egg and
immediately begin to incubate it. She
usually lays a second in a day or two and then the male will share the
incubation duties, each sitting for five or six hours at a stretch
until the first egg hatches. The chick is covered with yellowish down
and is able to walk in hours, and feed itself by the following day.
When the second chick hatches, the male usually leads the older one off
to prevent it from pecking at its younger sibling. Their legs grow at
an amazing pace and in a month they are as tall as their parents,
although their wings are still undeveloped. By mid July, however, they
are fully feathered and flying, and their family joins other crane
groups to feed in farm fields and pastures. They also eat insects and
mice in the fields, and they search in wetlands for plant tubers,
frogs, and snails.
When you see a “V” of large birds
flying in the sky, it is easy to tell
if they are sandhill cranes or the somewhat similar Canada geese. Both
species have long necks but the geese have shorter legs and tuck them
up into their feathers in flight, while cranes’ long legs always extend
out behind. When you see a single bird or two flying, it is either a
goose or sandhill separated from its flock, or more likely a great blue
heron. This bird also flies with its legs outstretched, but its neck is
always folded back while the crane’s is straight. Watch for them.
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August 4, 2009: Insect
Mimicry
Do you remember being taught in school
that some insects employ
elaborate disguises to escape predators or, alternatively, to capture
prey? One example often used was that of the viceroy butterfly—an
insect that very much resembles an unpalatable species and so
presumably escapes being eaten. The monarch butterfly larva feeds
exclusively on the bitter milkweed plant, thereby causing both the
caterpillar and later, the adult insect to have a disagreeable taste.
The viceroy has the same orange and black patterned wings, differing
only in having a straight band across its lower wings while that of the
monarch is uneven. There is also a third species, the queen butterfly
of the southwestern US, that has a remarkable resemblance to both,
particularly at rest with its wings closed.
After nearly a century of believing
and teaching the above scenario, it
has now been proven that there was a major flaw in the story—the
viceroy and queen butterflies actually taste as bad as the monarch, so
if there is mimicry involved it was not for the reason alleged. Some
now have suggested that in such cases there might have been an unknown
or now extinct model that all three copied, and that similarly
unpalatable species share warning colors or patterns to evade
predation, the advantage coming from the fact that predators need only
encounter one species to shun the others.
Another debunked theory concerns a
tropical butterfly that has
prominent eyespots on its underwings. It was long thought that these
markings fooled butterfly predators into thinking that they were seeing
an owl, but recent observation proved the insect never posed in such a
way as to display these spots. Thus, the assumption that such eyespots
on a variety of insects were protective has been brought into question.
Recently zoologists have shown experimentally that eyespot markings on
insects do not deter predators, so that even though they may look like
eyes to us, they don’t fool hungry diners.
There are some types of mimicry,
however, that involve using camouflage
as a means of hiding in plain sight from one’s predators. A large
family of moths called ‘underwings’ are active at night but spend their
days resting upside down with their wings flat against the bark of
trees. Their forewings are various mottled shades of grey and brown
that blend into the tree bark, and experiments have shown that they
will select backgrounds that help them disappear. Interestingly, the
moth’s hind wings that are hidden while at rest are usually boldly
patterned in orange, yellow, red, or white and these flash when the
moth is disturbed. Here, too, some biologists have suggested that the
sudden flash of color may momentarily startle or confuse a predator,
allowing the moth an extra moment to escape or that the bright colors
may deflect an attack away from the moth's body, although I suspect it
has more to do with finding a mate.
Perhaps one of the most impressive
local examples of insect mimicry is
found in the walkingstick. As its name suggests, this insect resembles
a brown twig, and frozen on a tree or shrub branch is almost impossible
for humans to detect. The fact that their numbers are held in check
despite their prolific reproduction indicates again that predators are
not so easily fooled. Walkingsticks range in size from a tiny,
half-inch-long species in North America, to a formidable 13-inch-long
insect in Borneo. This giant measures over 21 inches with its legs
outstretched, making it one of the world’s longest insects. Most of the
1300 varieties are found in the tropics and subtropics but several
species live in temperate regions where they thrive in forests and
grasslands, feeding on the leaves of oak, cherry, and black locust, and
sometimes clover.
We are most likely to see the northern
walkingstick, an insect that
grows to over 3 1/2 inches long, with the male being a brown color and
smaller than the greenish female. It has a long, skinny body and very
long antennae, about 2/3 the length of its body. To make the best use
of its camouflage, a walkingstick will straighten out its antennae and
front legs and remain motionless for extended periods. If attacked, it
can release a bad-smelling liquid, and also lose a leg and grow it
back. Its most important predators are birds but others include
lizards, mantids, and small mammals.
Adult walking sticks mate in the fall
and the females drop eggs, one at
a time, from the treetops. The eggs are small and look like black and
white beans and I read that one species of ant is known to carry the
eggs it finds underground where it eats small parts of them. The eggs
still hatch normally, and are actually protected by the ants. Any
remaining eggs survive over the winter in leaf litter, and nymphs hatch
the following spring looking like tiny adults though only a few
millimeters long. These nymphs crawl up onto small plants to feed and
as they get bigger they climb higher until they are in the tops of tall
trees. In late summer and early autumn, when they are full-grown, they
mate and lay eggs.
It is widely accepted that mimicry has
evolved because the mimic gains
protection or improves its ability to capture prey or acquire a mate,
but the mechanisms are poorly understood. It is certainly true that
insects that do not use this technique seem to continue to exist just
as well. Nature has used every imaginable means of survival for her
children.
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July 28, 2009: Microscopic Pond Life
Most of the plants and animals that
exist on our farm are invisible to
the naked eye and I spent a fascinating time this week peering at some
of them through our microscope. Our ponds teem with life and a drop of
water from the small one in the farmyard contained enough organisms to
keep me occupied for hours. Scanning the slide at low power required
constant adjustments to keep individuals in view as they zipped through
their mini-world. Most were single-celled, while others were much more
complex. Some swam about, feeding upon smaller organisms and decaying
organic matter, while others lay motionless, their green color
indicating that they contained chlorophyll and manufactured their own
food from solar energy.
There are typically a million
bacterial cells in a milliliter of fresh
water and untold numbers of fungi, but I was more interested in the
larger, more visible organisms. The name 'protozoa' is used for the
more animal-like creatures such as amoebas and ciliates, while the term
'algae' is used for the more plant-like microorganisms. But the
distinction is often vague as some have chlorophyll for photosynthesis
as do plants but can also feed on organic matter and are even able to
swim like animals. Nowadays, all these unicellular organisms that
cannot easily be judged to be animals, plants, bacteria or fungi are
usually called 'protists'.
The most numerous objects I found in
my drop of water were one type of
these protists—euglena. It is single celled and has a long flexible
flagellum used for locomotion although it can also move by flexing its
body and changing its body shape. It has a clearly visible nucleus that
contains the genetic material and a red eyespot that is composed of
photoreceptors and areas of orange-red pigment granules that can sense
light direction and intensity and signal the flagellum to swim towards
it. However, euglena also contains bright green chloroplasts that
transform light into energy and its numbers can become so great that it
turns the water of a pond green.
Besides the euglena, there were
several specimens of protozoa, and
paramecia in particular were plentiful. The paramecium can be
recognized by its sleek elliptical shape and its hairlike cilia that
propel it quickly through the water and guide food into its 'mouth'. It
is extremely active and difficult to observe because it swims in and
out of focus. Another I found to be particularly interesting was a
vorticella that somewhat resembled a flower on a slender stalk. It
extended tiny waving cilia that created a circular current in the water
that carried floating objects into its 'mouth', but when it seemed to
perceive a threat, its stalk contracted like a spring jerking it out of
harm’s way.
Most amazing was the microscopic bear
I discovered crawling around and
through a scrap of detritus. While the nickname of this tiny animal is
'water bear', it is properly called a tardigrade, and it lumbers about
on four pairs of stumpy legs. Some 750 species are known and specimens
have been found living in habitats as varied as the arctic, Antarctic,
the tropics and in hot springs. The water bear has piercing mouthparts
that are used to suck the juices from vegetation.
Tardigrades are an amazing group, and
all have an ability to withstand
extreme conditions. When their habitat dries out, they assume a
desiccated barrel-like form which can survive temperatures as low as
-272ºC which is almost absolute zero, or as high as 151ºC.
They have also withstood X-ray radiation 1000 times the human lethal
level and well as high vacuum. A number were successfully revived from
a piece of dried-up moss that had been kept in a museum for 120 years.
Recent studies have also shown that they can withstand 6000 atmospheres
pressure, which is nearly six times that of water in the deepest ocean
trench.
In a European Space Agency experiment,
several years ago, two species
of dried-up tardigrades spent 10 days on a satellite and then were
retrieved and rehydrated. The vacuum of space seemed to have had little
effect on them and 68% of specimens that were shielded from
higher-energy radiation from the Sun were revived within 30 minutes and
many went on to lay eggs that successfully hatched. However, only a few
survived full exposure to the sun's UV light, which is more than 1000
times stronger in space than on the earth's surface. Before this
experiment, only lichen and bacteria were known to be able to survive
exposure to the combination of vacuum and space radiation.
The largest creature I saw was a water
flea scooting about in the water
drop, but it, too, required the microscope to see its details. It had
long antennae that it used to push itself around, a large eye that
actually consisted of two compound eyes that were fused together, and a
two-piece protective shell. They are one of the most numerous
components of the plankton that drift about in bodies of water and form
the first link in the food chain for larger animals, fish, and birds.
There is still much to be learned
about the great numbers of
microscopic organisms, and different sources in the scientific
community on the internet provide varying definitions and data; still,
it is not necessary to identify or understand everything one sees to
marvel at this infinitesimal world that exists all around us.
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July 21, 2009: Meet the
Earwig
Twenty-five years ago, despite having
gardened for most of my life, I
had never seen an earwig except as an oddity that existed in the pages
of my bug book. Then when our daughter moved to Montana, she complained
bitterly about not being able to grow many of her favorite flowers
because the blossoms were being riddled by these insects. Later,
Madison friends reported having them in their raspberry patch, and now
I have become very well acquainted with this strange creature, and
chances are, you have as well.
There are some 1600 species of earwigs
around the world and ten in
North America, but the only species found in Wisconsin is the European
earwig. It was first recorded in the U.S. in Rhode Island in 1912
(although it was probably already present in some Western states by
then), and has spread throughout the cooler parts of the country,
moving into Wisconsin just over the last ten or fifteen years.
The earwig is an elongated, flat
brownish insect, about an inch in
length, and the first thing one notices is the pair of “pincers” on its
rear end. These are officially called “cerci”, a term that refers to
appendages that many insects such as crickets and mayflies, possess.
They often serve as sensory organs, but they may also be used as
weapons or mating aids. Crickets have particularly long cerci while
mayflies have an accompanying third tail filament that extends from the
tip of the abdomen.
The cerci of the earwig is the best
indicator of its sex as the females
have straight-sided forceps while the male forceps are larger and
strongly curved. The abdomen is flexible and muscular and is capable of
bending as well as opening and closing the forceps, and the insect uses
them to capture prey, defend its nest from intruders, in mating, and to
aid in tucking the membranous hind wing back under the short, leathery
fore-wing. Its wings are inconspicuous—the first pair being hard and
short, with a second fan-shaped pair folded under them, often with the
tips showing. Although it is seldom seen to fly, it can actually
flutter quite a distance, and probably does so at night.
Entomologists are particularly
interested in the earwig because of the
care they provide to their eggs and young. We all know that many ants,
bees and wasps live in colonies and carefully brood their offspring
until adulthood, but most other insects lay their eggs and leave them
to their own devices. Earwigs, however, are an exception as they are
solitary in nature but still tend their young.
In the fall, a mated pair of earwigs
will dig a short tunnel into the
ground, often with two chambers. The female then lays 50-90 shiny white
eggs in one of the chambers and both adults and eggs go into
hibernation for the winter months. In the spring, the female drives the
male from the nest and actively busies herself with the eggs, cleaning
them often and rearranging them. The female may even move them to
different parts of the tunnel, perhaps for temperature regulation.
Whatever the reason, eggs that are not
cared for have a much lower
survival rate than eggs that are tended, as the eggs are often attacked
by mold. Females not only clean any mold from the eggs, but deposit a
fluid on them as well. European earwig females usually do not eat
during this period, and often seal the nest entrance as an added
defense against intruders. She will defend her nest vigorously, but if
the nest is disturbed repeatedly, she will eat the eggs and abandon it.
After the eggs hatch, the nymphs
remain in the nest until after their
first molt. The young earwigs resemble their parents, but are lighter
in color, lack wings and have only tiny pinchers. The female initially
feeds them by regurgitation but then brings in food. After molting the
first time, the nymphs leave the nest, and the female no longer shows
any interest in them. The young mature in September and early October,
and dig into the soil as pairs to construct their nests.
This earwig is found throughout
Europe, but seldom is present in
bothersome numbers. It has become a serious pest in parts of the United
States, however, because even though it eats some insects such as
aphids, it seems to prefer garden flowers and vegetables. It hides
during the day and roams at night, and while it is chiefly an "outdoor
insect", it is frequently brought into the home hiding among plant
leaves. Fortunately, although new populations initially tend to build
to very high levels, they then usually decline.
Son, Dick, tells me that an old Star
Trek movie featured a giant alien
earwig that was dropped into Chekov's ear, but it is only a myth
that earwigs crawl into the ears of sleeping people and bore into their
brains. They may not cause fever and insanity, but these insects do
suffer from a bad reputation, not only because they damage plants but
because they can emit a foul-smelling, yellowish brown liquid from
special glands and can inflict a pinch from their ferocious-looking
pinchers. They join the Japanese beetles, Asian ladybugs, and the host
of other new arrivals that add spice to our gardening and outdoor
living.
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July 14, 2009: Hummingbirds
In past weeks, our three hummingbird
feeders had been beehives of
activity with one or two males trying to dominate each one, and hungry
females and youngsters having to sneak in whenever they could. Then we
noticed a considerable decrease in their numbers and received several
calls from readers with the same experience, worried that something had
happened to them. I decided to research the missing birds but found no
explanation on the web, and today they seem to be back with no clue as
to where they might have been in the interim.
The ruby-throat is the only
hummingbird that nests east of the
Mississippi River and can be found in open woodlands, forest edges, and
meadows, and in parks, gardens, and backyards. It is a tiny bird that
weights only 1/8 ounce, and has a slender, slightly down-curved bill
and fairly short wings that don’t reach all the way to the tail when it
perches. Both sexes are basically iridescent green above, with gray
below, but the adult male also has feathers on his throat that often
appear to be black but flash brilliant red or orange in the sunlight.
The bill of the ruby-throat is one of
its most distinctive features. It
measures almost inch in length but the bird has considerable control
and can open just the tip to snag insects out of the air or off of a
flower. Also, the bill has a hollow channel down the middle so
that the tongue can slide in and out without the bird having to open it
at all. A hummingbird laps up nectar with its long tongue by extending
and contracting it up to 13 times per second and the tip is split and
somewhat broadened and brushy allowing capillary action to draw in more
fluid.
An adult ruby-throated hummingbird may
eat twice its body weight in
food each day, which it burns up to sustain its rapid wing beat and
energetic movements. Hummingbirds feed in many small meals and spend an
average of 10-15% of their time eating and 75-80% resting and
digesting. Nectar is a poor source of nutrients but gives them the
energy to find the insects and spiders that will meet their needs for
protein, amino acids, vitamins, and minerals. If the average human were
to consume as much food relative to his size as a hummingbird, he would
have to eat 228 pounds daily!
Flight muscles make up about 25-35% of
a hummingbird's overall weight,
about 10% more than in other flying birds. They are also unusual in
that they contain all red muscle fibers and no white; other birds have
at least some white fibers mixed in. Red fibers are adapted for
sustained use, while white fibers allow for sudden, short-term energy
bursts. Flightless birds such as chickens have breast muscles
consisting of white fibers only. The hummingbird has long, blade-like
wings that connect to the body in tiny ball-and-socket joints. These
allow the wings to rotate almost 180°, enabling the bird to fly not
only forward but also straight up and down, sideways, and backwards,
and to hover in front of flowers as it feeds on nectar and insects.
During hovering, ruby-throated hummingbird wings beat 55 times each
second, 61 times when moving backwards, and at least 75 times each
second when moving forward.
The heart beats about 250 times per
minute while at rest, and about
1,220 per minute while flying. On cool nights, the body temperature of
hummingbirds can drop safely from a daytime norm of about 105 degrees F
to an overnight low of about 70 F degrees. This condition, known as
"torpor," also allows the heart and breathing rate to slow and lowers
the basal metabolism so the hummingbird burns much less energy
overnight.
Ruby-throated hummingbirds do not form
breeding pairs, and a male will
establish a territory and court any females that enter it. He does this
by erecting his red throat feathers and engaging in looping dives above
her head. This spectacular “dive display” may climb to 8 to 10 feet
above and 5 to 6 feet to each side of the female, and his wings may
beat up to 200 times per second. A study at UC at Berkeley in Science
Magazine this month stated that one hummingbird experienced forces nine
times the force of gravity as it pulled out of its dive, traveling 385
body lengths per second (in contrast to a fighter jet on afterburner
that only reaches 150 body lengths). If the female is receptive, they
will mate and that is the extent of the male’s participation in family
life. The female will establish her own territory and raise their
offspring.
The walnut-sized nest is usually
composed of bud scales bound with
spider's silk, with lichen on the exterior and lined with dandelion,
cattail, or thistle down. The female will lay two white, pea-sized eggs
that hatch in 2 weeks, revealing tiny naked and blind chicks. The
mother feeds them by regurgitating insects and nectar deep into their
throats and they grow quickly, equaling their mother's weight in only
10 days. The young are ready to leave the nest when they are twenty to
twenty-two days old and the mother spends another 10 days or so
teaching her young to find food before they become independent.
Due to their small size and brilliant
plumage, ruby-throated
hummingbirds have been hunted throughout their history. The population
has never become threatened, however, and there are an estimated
7,300,000 worldwide. They give us much pleasure as they come to our
feeders and we hope they will continue to spend their summers with us,
even if they disturb us with their unexplained disappearances.
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July 7, 2009: Eeek, A Skunk!
We share our farm with a variety of
animals—some that we see regularly
such as the deer, coyotes, rabbits, and squirrels, while others that
are far more reclusive and seldom allow us a single sighting. One very
common species is the stripped skunk, and we are often alerted to its
presence only because of its distinctive smell.
The skunk was previously thought to be
a close kin of the weasels, but
recent research with mitochondrial DNA suggests that this is not true
and it now is classified in its own family. There are four species in
North America— spotted skunks, hooded skunks, the very scarce hog-nosed
skunks, and striped skunks. Actually, all skunks are striped, even from
birth. They may have a single thick stripe across back and tail, two
thinner stripes, or a series of white spots and broken stripes (in the
case of the spotted skunk). Still, only the species named “striped
skunk” is the type common in Wisconsin. Its fur pattern is a white
strip that starts at the forehead and splits into a V shape as it
travels down the back.
Striped skunks are born hairless, but
their stripes are already
visible, and the length and width of stripes varies with each
individual. There are also some skunks that are completely black or
completely white. Although they have excellent senses of smell and
hearing, they have poor vision and cannot see objects more than about
10 ft away. Striped skunks are both solitary and nocturnal. They are
also short-lived; fewer than 10% survive for longer than three years
and roughly half of all skunk deaths are caused by humans, either by
vehicles on the roads or as a result of shooting or poisoning.
Skunks have adapted to human
habitation and are not above taking
advantage of its benefits. Part of what has made them such a successful
species is the ability to eat almost anything—insects, small mammals
and birds, eggs, crustaceans, fruit, vegetables, carrion, and even
human garbage. They are primarily active at dawn and at dusk and have a
home range of about a square mile. Although they mate in late
winter or early spring, a female can store the male’s sperm and delay
pregnancy for some weeks so that the kits are usually born in May. The
mother is very protective of her offspring, and will often spray at any
sign of danger, while the male plays no part in raising the young and
may even kill them. The kits are weaned at about two months, but
generally stay with their mother until they themselves are ready to
mate, the following spring.
Skunks are slow and placid in their
movements, but they can afford to
be relaxed as each has special anal glands that hold about a tablespoon
of a fetid, oily, yellowish musk that is a mixture of sulfur-containing
chemicals that have a highly offensive smell (it has been described as
a combination of rotten eggs, garlic and burnt rubber). When
threatened, the skunk will face the intruder, elevate its tail, chatter
its teeth, and stomp the ground with the front feet. If this doesn’t
work, the skunk will twist around, raise its tail straight up, and
spray with remarkable accuracy. The stream can travel 10 to 15 feet and
in addition to the terrible smell, it causes intense pain to the eyes
and even loss of vision as well as nausea and vomiting. Only the great
horned owl (or an inexperienced young coyote or dog) will attack a
skunk.
Skunks are reluctant to use their
smelly weapon, as they carry only
enough of the chemical for five or six uses and then require more than
a week to recharge. Therefore, when possible, it is to a skunk's
advantage simply to warn off a threatening creature without expending
scent. Interestingly, skunks will not spray other skunks (with the
exception of males in the mating season), opting to fight each other
with tooth and claw.
Many of the same warnings that are
given to avoid visits from bears and
wolves also apply to skunks. Never leave pet food outside; never
discard edible garbage where skunks can get to it; keep pets indoors at
night and pet doors closed to block access by a skunk; keep fruit trees
picked and don't leave rotted fruit on the ground; and don’t fill bird
feeders in the summer as skunks may be attracted to them and to the
birds and rodents that use the feeders. Incidentally, healthy skunks
cannot “carry” rabies and only sick, rabid animals are able to transmit
the disease, and then only through bites, as the virus is in the
saliva. The Centers for Disease Control and Prevention report about
1500 cases of rabid skunks each year but almost all recorded cases of
human rabies have been traced to dogs or bats.
Should you have the misfortune to need
it, there is a very effective
antidote to skunk smell. Apply a mix of 1 quart 3% hydrogen peroxide,
1/4 cup baking soda, and 1 tablespoon liquid hand soap, let soak, and
then rinse. Use immediately and don’t stopper up any leftover as the
hydrogen might explode. I hope you will never need it!
(Incidentally, a news bulletin this
week tells us that wolves have been
replaced on the federal endangered species list until challenges have
been ruled upon by the courts, so that controversy continues..)
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June 30, 2009: Wolves and Bears
in our Yards
A few years ago, we would never have
imagined seeing black bears or
wolves in our backyards or along the roads here in the River Valley
area, but today such sights are being increasingly reported. Most are
young males that are searching for unclaimed breeding territories after
being chased off by dominant males farther north. They usually return
northward when the breeding season ends, but more and more individuals
seem to be taking up residence.
A wolf pack's territory may cover
20-120 square miles, about one tenth
the size of an average Wisconsin county. The timber wolf is a social
animal, living in a family group or pack usually made up of six to ten
animals—a dominant male and female, offspring from the previous year
and the current year's pups. A young male can stay with its family and
work its way up to dominance, or it can leave the pack and try to find
a mate and a vacant area in which to start its own pack. A wolf knows
where its territory ends and another begins by smelling urine and feces
left by other wolves, and when it trespasses in another pack's
territory it risks being killed.
Before Wisconsin was settled in the
1830s, 3,000-5,000 wolves lived
throughout the state but by 1960, wolves were declared extirpated from
Wisconsin. In 1974, however, the value of timber wolves in the natural
scheme of things was recognized on the federal level and they were
given protection under the Endangered Species Act. The animals began to
move in from Minnesota, and in the last 30 years, their numbers have
expanded well beyond the goal set in the 1999 Wisconsin Wolf Management
plan. The Wisconsin Department of Natural Resources now estimates that
there are about 650 wolves across the state in 143 packs. Last year,
wolves in Wisconsin and other portions of the western Great Lakes were
removed from the list of federally endangered and threatened species,
returning management authority to the states and tribes for dealing
with problem wolves that threaten livestock and pets.
When Wisconsin became a state, black
bears were also found in every
county, though less frequently in the southern prairies and oak
savannahs. Early Native Americans honored the bear as a supernatural
being and prized their hides for robes and the meat and oil for
cooking, fuel and medicines. The earliest white settlers, too, placed
great value on bear meat and skins, but as more humans flooded into the
area, the animals caused increasing problems. Bounties were established
as well as market hunting, and black bears were exterminated from
Wisconsin's southeastern counties by 1860 and from the central and
southwestern counties by the 1890s. In the hill country portions of
Sauk and Richland counties they survived until well after 1900, but
bear numbers continued to decline until they reached their lowest point
in 1915. In 1942, the Department released black bear cubs back into the
wilds of Door, Adams, Jackson and Wood counties and began to regulate
hunting, allowing the population to recover.
Adult black bears typically weigh 250
to 500 pounds and when standing
on all four paws, measure 2 to 3 feet tall at their shoulders. They
prefer to live near forest edges where the ground cover is thick and
lush with abundant nuts and berries. However, because people continue
to invade native northern habitats for vacations and second homes,
bears are being pushed into central Wisconsin and even as far south as
Portage, Spring Green or other areas near major rivers that act as
travel lanes.
Preliminary results of a recent
two-year cooperative study of Wisconsin
black bears suggest that the population may be approximately 13,000
animals, almost double what had been previously estimated. The
DNR-funded study was conducted by University of Wisconsin-Madison
Wildlife Ecology graduate student Dave MacFarland under the guidance of
Dr. Timothy Van Deelen. Some 3,500 baits marked with tetracycline were
set out across the state’s bear range in 2006. (Tetracycline, when
ingested, is harmless to bears but leaves a telltale line in a bear’s
bones). Successful bear hunters in 2006 and 2007 were asked to provide
a section of a rib bone for analysis from bears they harvested, and by
comparing the number of baits consumed in a season to the number of
harvested bears showing the tetracycline marker, scientists were able
to calculate the new population estimate.
Biologists offer the following advice
for avoiding unwanted encounters
with black bears and probably wolves, as well: never leave pet food
outdoors; hang bird feeders at least 10 feet off the ground, and then
only during the winter; store meat waste in the freezer and place in
the garbage container just before pickup; do not leave pets out after
dark. If you encounter a black bear or wolf, make noise so you don’t
surprise it, and then back away slowly or take shelter in a vehicle or
structure. Respect them as wild animals and enjoy them safely from a
distance.
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June 23, 2009: The Good and Bad About Wasps
We found a strange looking papery
object hanging from the barn door
lintel this week. It was about the size and shape of a large hen’s egg
on end and had a 1/2” diameter open tube extending out the bottom. We
watched it several days as it grew, but on the third day it
disappeared, victim of someone who thought the dangers of hosting a
wasp colony in such a high traffic area much greater than the benefits
to my scientific observations. Phil Pellitteri of the University
Entomology Department identified it as the nest of a bald faced hornet,
and told me that it eventually would have been transformed into one of
the basketball-sized nests often seen hanging in trees, so the sooner
it was removed, the better.
Wasps are probably not on your list of
favorite insects and the common
stinging types such as the yellow jackets, and hornets are hard to
ignore. Nevertheless, those are only two of the hundreds of wasp
species that live in Wisconsin and you probably don’t even notice most
of the others. Wasps come in a variety of colors, sizes, and shapes and
are cousins to bees and ants, although wasps have smooth body surfaces
while bees are quite hairy, and most wasps sting while most ants do
not. In general, wasps are parasites or parasitoids as larvae
(parasites feed upon a host without causing undo harm while parasitoids
kill it as they develop), and feed only on nectar as adults. Some wasps
are also attracted to over-ripe fruit, nectar, and carrion, and in many
species the larvae provide sweet secretions that the workers eagerly
lick up.
There are two major types of wasps,
social types such as paper wasps,
hornets, and yellow jackets, and solitary wasps. The social species
develop into large colonies by the end of the season, while the females
of the solitary species lay single eggs on unsuspecting hosts and leave
their offspring to fend for themselves. Unlike bees and ants, only
fertilized females are able to survive a northern winter and so
generations begin anew each year with solitary queens.
In the early spring, the queen of a
social species creates a paper-like
canopy under which she attaches a number of cells, depositing a single
egg in each. She continues to add more cells and also feeds the
hatching larvae bits of caterpillar or other such soft material. In a
few weeks the larvae mature into sterile adults that take over the
duties of enlarging and maintaining the nest, foraging for food and
caring for the offspring, while the queen devotes herself to producing
more eggs.
Unlike honeybees, wasps have no wax
producing glands to form their
cells; instead, many create a paper-like substance from fibers gathered
from weathered wood, cardboard or paper and softened by chewing and
mixing with a starch in their saliva. The workers spread this mixture
with their mandibles and legs, forming it into 3 or 4 tiers of combs
within a thick, multilayered outer shell with a single opening at the
bottom. As the inside cell structures get larger, they will remove the
inner layers and recycle them, adding to the outside covering and
continually making the nest larger. Nests can be quite colorful as
wasps will gather nest materials from different sources.
The workers also guard the nest and
collect nectar and soft insects to
feed the larvae. At first colony growth is slow, but the numbers
increase rapidly by mid-summer as successive broods of workers emerge.
Peak worker population of the bald faced wasp may be 400 by the end of
the summer, but other social wasp colonies can have populations of
several thousand. In the fall, the queen lays eggs that produce males
and new queens and when these mature, they leave the nest and mate. The
newly fertilized queens go into hibernation while the workers, the old
queen and the males die with freezing temperatures.
In contrast to the social wasps that
tend to be aggressive and sting
when disturbed, solitary wasps generally attack humans only when
seriously threatened. The fertilized female lays a single egg on or in
a food source and there is no interaction between the resulting larva
and any adult. The mud dauber builds mud cells that it usually
provisions with small spiders. The cicada killer paralyzes a cicada and
drags it to its nest in the ground before depositing an egg. Other
solitary wasps use grubs, caterpillars, and ants as food for their
larvae. In some species, male eggs are selectively placed on smaller
prey, leading to males being generally smaller than females. In
contrast to these predatory wasps, another large group utilizes plants
to provide suitable housing and food for their young often in the form
of galls. Plant galls are abnormal growths of plant cells that usually
develop in response to egg laying or larvae feeding by a wasp or other
insect, and if you cut one open, you can often discover the larva
inside.
Although a few of the stinging species
are considered nuisances, wasps
are important members of our natural system. Yellow jackets and paper
wasps may bother us, but they also prey on caterpillars and other
larvae that can inflict considerable damage in our gardens, fields, and
forests. Most other species are either parasitic or predaceous and
therefore play a vital role in limiting the populations of thousands of
insect species. Wasps feed on flower nectar, often thereby spreading
pollen, and more importantly, many parasitic wasps have been cultured
and used in the biological control of agricultural pests. They do far
more good than harm.
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June 16, 2009: All About Insect Wings
Insect wings are a marvel of beauty
and engineering. They come in all
shapes and sizes, but the ones I particularly appreciated these past
two weeks were those of the Cecropia moths that have hatched in my
rearing cage out in the shed. More than a dozen of the big silk moths
have emerged from the cocoons in which they spent the winter months,
the adult stages of the ravenous caterpillars that kept me busy last
summer supplying them with sufficient food.
How such a larva could become a
delicate moth has always seemed almost
miraculous to me but scientists have uncovered some of the secrets that
help us understand the process. The body of a caterpillar is divided
into segments, each of which has paired openings in its side that lead
into the respiratory system. Tiny wing discs replace the openings on
the second and third segments behind the head, and when the larva is
almost fully grown, the discs increase dramatically in size and a
system of branching tubes develops inside them. Finally, when the larva
spins its cocoon and then sheds its skin a final time revealing the
pupa or resting stage, internal pressure forces these budding wings to
the outside and they adhere tightly to its surface. Within hours, the
pupal skin hardens and the wings are firmly attached so as to appear to
be a part of the whole.
While the developing moth is in the
pupa stage, the wing forms a
structure that becomes compressed from top to bottom and pleated from
end to end as it grows, so that it can rapidly be unfolded to its full
adult size. In most cases, a characteristic network of longitudinal
veins with cross-connections that are extensions of the body's
circulatory system runs throughout the wing tissue. After the moth
emerges, it hangs quietly from a support and pumps the insect
equivalent of blood into these veins, expanding and firming up the
wings into their proper shape. The veins provide strength and
reinforcement during flight and their shape, texture, and arrangement
are quite distinctive among the various insects and therefore highly
useful as aides for identification. The spaces between the network of
veins are filled with a transparent or brownish membrane only one or
two cells thick that has its own special functions.
Most butterfly and moth wings are
covered with a dense mosaic of tiny
individually colored scales that form striking color patterns and
designs. The scales grow out of the membrane between the veins and are
comprised of a basal socket cell and a flattened scale cell. In the
case of butterflies, these scales are organized into orderly rows that
radiate out from the base of wing while most moths show a random
distribution. These scales vary considerably in size, shape and
structure and are generally held at a 45-degree angle to the wing
membrane. Each scale cell is of a single color and may be pigmented
with black and brown, or may show blue, green, red or iridescence
because of the microstructure of its surface. The scales cling somewhat
loosely to the wing and come off easily without harming the insect.
How and why insect wings evolved is
not well understood. Some
scientists theorize that they may have initially developed from
multi-branched moveable gills on primitive aquatic nymphs. However they
came about, biologists believe that all the various wings types
initially had the same ancestor; in other words, insect wings evolved
only once in history. Fossil records show that the early insect
wing had 8 pairs of main veins, each of which fused near the wing base
and then diverged toward the tips, and all subsequent wings have shown
some degree of reduction in the number of veins.
Wings may be membranous,
parchment-like, hardened, fringed with long
hairs, or covered with scales. They serve not only as organs of flight,
but also may be adapted variously as protective covers as in beetles,
thermal collectors as in butterflies, gyroscopic stabilizers as in
flies, or sound producers as in grasshoppers.
The damselfly and dragonfly both have
two pairs of clear wings that are
about equal in size and shape, with five main vein stems. Grasshopper
forewings are tough and leathery and cover membranous hind functional
wings when at rest and are held out of the way in flight. A beetle's
rigid wing covers are modified forewings and in flight, they are held
out at an angle. At rest, the hidden hind functional wings are folded
longitudinally and transversely, and when needed, are rotated forward
on their bases into flight position, an action which spreads the wings.
A fly has only one pair of functional wings and its hind wings are
reduced to small club-like structures that vibrate rapidly during
flight, acting as organs of balance.
Insects develop wings only at certain
times of their lives, and not
always then, and the process is one that has been the subject of much
study. Take time to look at the various types on the bugs that might be
flying around in your house and yard. As our grandkids often say,
“They’re awesome!”
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June 9, 2009: Mosquitoes,
Mosquitoes, Oh My!
Those of you who have visited the farm
know that we have two artificial
ponds on our dry hillside, one in the farmyard by the porch and the
other in the wildflower garden. We enjoy the parade of birds and
animals that come for drinks and showers in the waterfalls, but
onlookers often ask how we deal with the mosquitoes they believe must
breed in them.
The northern house mosquito breeds in
water sitting around in tin cans,
discarded tires and quiet ponds, but we have a number of creatures that
usually protect us from these biters--in, on, and above the water. The
greatest reduction in numbers of mosquitoes takes place in the egg and
larval stages where small fish and many water insects gobble them up by
the mouthful. Water scavenger beetles and giant water bugs are
effective predators as well as immature dragonflies and damselflies
that are wingless nymphs with large heads, compound eyes, six spindly
legs, and big appetites.
Backswimmers and water boatmen with
their two oar-like hind legs are
also voracious feeders on mosquito larvae and other small creatures.
Both insects spend most of their time in the water, using their hind
legs with long hairs that are modified for swimming, and breathing air
trapped in abdominal pockets as they dive for lengthy periods. They
look and act much alike, but water boatmen swim dorsal side up, while
backswimmers swim upside-down.
Only about one in every 200 immature
mosquitoes survives to reproduce
and if a nymph survives to adulthood, a whole host of other predators
is waiting to grab it. Water striders are long, wingless insects that
scoot about on the surface of the pond, snatching up any emerging
insect and also any female mosquito that alights to lay eggs. They are
easy to identify by their long second and third pairs of legs that jut
out from their sides and have water-repellent hairs that hold tiny air
bubbles, allowing them to skate on the surface of the water.
An adult dragonfly is perhaps the most
efficient adult “moe” killer and
patrols its territory tirelessly. It shapes its six hairy legs into a
basket and overtakes flying prey from behind, snaring the potential
meal in its legs. Dragonflies have large compound eyes (each large eye
is made up of some 30,000 smaller ones!), two pairs of strong
transparent wings, and an elongated body. They are usually found around
lakes, ponds, streams and wetlands because most of a dragonfly's life
is spent beneath the water's surface as a nymph that uses extendable
jaws to catch whatever happens by. As adults, however, they wander over
large areas to find flying prey. Damselflies are often confused with
dragonflies, but most damselflies hold their wings together above the
torso when at rest whereas most dragonflies at rest hold their wings
horizontally. Today's dragonflies look much like their ancestors that
lived nearly 300 million years ago although even the largest is much
smaller than one ancient species that had a 27-inch wingspan.
Frogs, toads, and tree frogs use their
long sticky tongues to pull in
passing flyers, and eagerly gobble up almost anything that moves, but
they usually take prey that is larger than tiny mosquitoes. On the
other hand, birds such as chimney swifts, barn and cliff swallows, and
purple martins feed on all types of flying insects and can consume 60
per hour or a whopping 850 per day. Whip-poor-wills used to be our
favorite flying insect eater, but the past few years they have
abandoned our hilly farm and their numbers are reportedly declining
across the country. They and nighthawks have large heads and eyes and
exceedingly wide mouths that they use as scoops for catching insects
including mosquitoes in midair.
Bats also work to keep mosquito
populations under control. It has been
estimated that just one bat can eat more than 1,000 mosquitoes in an
hour and they seem to be the primary food for some species. Bats can
see quite well but rely on their hearing at night. Its echolocation
system makes use of ultrasonic sound pulses and echoes to locate
objects and enables bats to use their large and well-developed ears to
navigate and catch moving prey in total darkness. Bats echolocate
either through their noses or through opening their mouths in flight
and emit a series of ultrasonic pulses that bounce off objects such as
buildings, branches, and prey including swarms of mosquitoes.
Using the information gained from these echoes, a bat can maneuver to
catch prey while avoiding flying into objects. The common little brown
bat consumes half of its body weight in insects in a single evening and
even more if nursing.
With all of these guardians, you would
think we would never see a
mosquito, but the fact is we are sometimes inundated. There are more
than 50 mosquito types living in the state according to Phil
Pellitteri, University of Wisconsin extension entomologist, and the
most bothersome are sometimes called "floodwater" mosquitoes, because
if a pond or riverbank dries up, any eggs there can remain dormant for
months or years until they are again flooded. Once the rains begin, the
pests can appear in less than two weeks, and as many as 100 mosquitoes
can emerge per square foot of water surface each day. These can migrate
10 to 20 miles from their breeding site and on occasion, a flight of
these pests is blown up into our hills to plague us. Of course, this
delights all the mosquito diners and our pain is their gain...
---------------------------------------------------------------
June 2, 2009: Luna Love and More
It is hard to ignore the unsightly
webbed caterpillar nests in many of
our young trees this year. These are the work of eastern tent
caterpillars and they seem to be more numerous than usual. Ugly as
their shelters may be, these insects have an interesting story.
The caterpillar over-winters as an egg
among several hundred others
under a shiny, black varnish-like cover wrapped around a twig. It
hatches in the early spring as the leaves of its host tree—usually a
wild cherry--are just unfolding as it can only digest young leaves and
must complete its larval development before the leaves become too
mature. All the caterpillars from one egg mass stay together and spin a
silken tent in a tree crotch at a site in the early morning sun. The
position of the tent is critical because studies have shown that when
the body temperature of a caterpillar is less than about 15 °C,
digestion cannot occur, a common situation in the early spring.
The tent consists of separate layers
of silk separated by gaps and the
conditions in these compartments vary considerably. Caterpillars can
adjust their body temperatures by moving from one compartment to
another. On cool mornings they typically rest in a tight group just
under a sunlit surface of the tent where the temperature may be as much
as 50 °F warmer than the surrounding air. Later on in the spring
when it may become too hot for them at midday, the caterpillars may
retreat to the shaded outside surface of the tent. Leaves consist
largely of non-digestible material and it has been estimated that tent
caterpillars void nearly half of the energy they ingest. While tent
caterpillars can nearly defoliate a tree when numerous, the tree will
usually recover and put out a new crop of leaves.
The larvae are hairy caterpillars,
black with a white stripe down the
back, brown and yellow lines along the sides, and a row of oval blue
spots on the sides. They emerge to feed on leaves in the early morning,
evening, or at night if it is not too cold. Immediately after feeding
the caterpillars return to the tent and gather in the sunlight to
digest their meals. Studies have shown that eastern tent caterpillars
lay down a pheromone trail as they crawl about in search of food,
allowing them to find their way back to the tent. This chemical trail
also leads other hungry caterpillars to the food source and is
remarkably similar to the pheromone trails that are used by ants and
termites to alert nest mates to the discovery of food. As the larvae
feed on the foliage, they increase the size of the web until it is a
foot or more in length. In 4 to 6 weeks the caterpillars are about
2-1/2 inches long and begin to wander away from the nest in search of
protected areas to spin their cocoons.
The reddish-brown adult moth emerges
from the cocoon about 3 weeks
later. After mating, the females lay their eggs on small branches and
then die, usually in less than 24 hours. Shortly after the eggs are
deposited, tiny embryos begin to develop inside the eggs but then lie
dormant until the following spring. In northern areas, the larvae are
highly freeze tolerant and can withstand midwinter temperatures as low
as -40 °C.
Tent caterpillars exhibit boom or bust
population dynamics. The most
notorious is the forest tent caterpillar. During outbreaks, these can
become so abundant that they are capable of completely defoliating tens
of thousands of acres of forest. Despite the name, the forest tent
caterpillars do not spin tents; instead, they form a silken mat on the
trunk or branch, and here they congregate when at rest or during
molting periods. Region wide outbreaks have occurred at intervals
varying from 6 to 16 years in northern areas when they have stripped
trees and then attacked shrubs and even the leaves of cultivated fruits
and vegetables.
The moths of both these species are
relatively small and unremarkable,
but I had several entirely different and far more desirable moths
emerge from their cocoons this week. I had raised the caterpillars of
three types of giant silk moths last summer, over-wintering their
cocoons in a secure cage in an outbuilding. First to appear were the
lunas—delicate white furry insects with four-inch lime green wings that
tapered to long tails. Fortunately, the first two were male and
female and immediately mated. They remained attached throughout
the next day and I quickly placed the female in a paper grocery bag to
collect some of her eggs when they separated at dusk.
By the following morning, she had laid
several dozen eggs and two more
females had emerged in the cage. At that point I carried the cage and
paper bag to the ridge where we have seen lunas other years and
released them, hopefully to add to our native population. The
eggs should hatch in the next few days and I will care for the babies
until they get a bit bigger and then place them on one of our birches
under netting. Now I am awaiting the arrival of the polyphemus and
cecropia moths that should come out very soon.
------------------------------------------------------------
May 24, 2009: Babies, Babies, Babies
Who among us has not come upon a
seemingly helpless baby bird
fluttering along the ground—or practically stepped upon a baby rabbit
huddled in a clump of grass—or discovered a tiny squirrel beneath a
tree? This is the time of year that such chance meetings occur and we
often are unsure how to react when a young animal seems to be
neglected, injured, or in need of help. Wildlife experts tell us that
the best policy is to leave such creatures alone unless the animal is
in imminent danger from a predator or other serious threat. Most of the
youngsters encountered in the wild are not orphaned or abandoned and
their mothers may be hidden nearby or will return shortly.
Nestlings that which lack feathers and
are covered with down are
sometimes found on the ground, and clearly need the shelter and warmth
of their nest. This is one case when you can do them a service by
lifting them carefully and replacing them. Despite the common belief,
most birds have a poor sense of smell and minimal handling will not
cause the adults to abandon them. As the babies become fledglings and
are fully feathered, however, they may leave the nest and hop along
branches or the ground. At this point, they are usually able to find
cover and the adult birds will continue to care for the young birds, so
it is best to leave them alone.
A nest of baby cottontail rabbits may
seem to be deserted because no
adults are seen for extended periods, but the fact is that mother
rabbits only feed their young at dawn and dusk and are seldom at the
nest during the day. Rabbit milk is very rich so the babies require
only a few minutes to nurse, and mother rabbits do not cuddle the
babies to keep them warm, as do some mammals and birds. The young
rabbits grow quickly and will leave the nest within two to three weeks,
and if a small rabbit is seen outside of a nest with its eyes open and
ears standing up, it is most likely capable of being on its own.
Fawns will move very little their
first few weeks, relying on their
lack of scent and spots for camouflage. During this time the mother
wanders about but will return frequently to nurse. We had an
interesting experience some years ago when our old collie found a very
young fawn under our deck. We discovered them lying side-by-side and
called a wildlife rehabilitator for advice. She suggested the baby was
probably ill and thought possibly its mother had brought it to us for
help although most people would contend that deer are not that
intelligent. The rehabilitator came for it and found it badly infested
with botfly, a parasitic fly that sometimes attacks newborn animals
through their umbilical cords. They worked much of the night to save
it, unfortunately without success and it died before morning.
Both squirrels and raccoons nest in
trees and sometimes fall for one
reason or another. The mothers of both species will retrieve their
young and carry them off to new quarters, and so neither should be
picked up unless it is known that the mother has been killed.
Young opossums are seldom found, as
they do not leave the mother’s
pouch until two months of age. At four months of age when they are
approximately seven to nine inches long, they leave the mother and are
independent.
Ducks sometimes choose unsuitable
sites to nest, but usually seem to be
able to lead their offspring safely to water. The recent news story of
the man who caught each duckling as it jumped off a high nest was one
of the more spectacular situations, but persons who live anywhere near
a pond or lake often find themselves host to a family each spring. The
hen will stay with her brood until the ducklings are able to fly,
approximately two months after hatching.
It is well to understand that no
person may possess live native wild
animals without a license or permit from the Wisconsin Department of
Natural Resources, or a migratory bird without a permit from the United
States Fish and Wildlife Service. If it is absolutely necessary to help
a young animal that is injured or its mother has been killed, a person
may legally have the animal in their possession for up to twenty-four
hours for the purpose of transporting it to a licensed wildlife
rehabilitator or for release in a more appropriate location. Linda
Bethke in Prairie du Sac will care for bird and reptiles, (608)
643-8390, but I was not able to find any trained person in Sauk County
that can help with other animals. You could call the DNR Bureau of
Wildlife Management at 608-266-8204 if you need assistance.
Most young animals that seem to be
abandoned do not need help, and our
intervention may actually cause it distress and harm. Mothers take care
of their young in a variety of ways, and what may be seen as abnormal
behavior may be just a part of the animal’s routine. A youngster should
never be removed from the wild unless absolutely necessary, cute as it
often might be.
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May 17, 2009: Meet the Yellow
Lady Slipper
Why all the fuss about yellow lady
slippers? The chance to acquire one
of these almost exotic wildflowers has brought buyers from miles around
to our plant sale, and several spent the night nearby so as to be sure
to be among the “first-come-first-serve” customers. This delicate
orchid blooms early in May, sending up one or two showy flowers from a
single, leafy stalk. The blossoms have a brilliant golden yellow lip
that is enlarged into a hollow, inflated pouch often speckled inside
with crimson, and two spirally twisted side petals and two broad
sepals, one above and one below the pouch that may vary in color from
purplish brown to green.
The yellow lady slipper is one of
several dozen Wisconsin relatives of
the exotic tropical orchids. Most are relatively shy and unobtrusive,
but the pink, yellow, and showy lady slippers are spectacular. We found
several small patches of the yellow species when we acquired the farm
in the early 70's, and they have appeared elsewhere through the years.
I have since separated and transplanted clumps until they now flourish
in many sections of our woods.
Orchids are thought to be one of the
first of the flowering plants to
evolve and have spread into every corner of the world except
Antarctica. Some adapted to living in the ground or under it, some high
in trees, on mountains and in bogs, in tropical rainforest or lush
grassland. There are around 35,000 different species of orchid, ranging
from plants only a fraction of an inch tall with flowers the size of
pinheads to others with 10 foot stems whose flower stalks stretch to 15
feet. Their leaves can resemble blades of grass or the foliage of
lilies and irises, to which orchids are related.
Botanists have placed all these
various species in the orchid family
because of the structure of their flowers. They have an outer whorl of
3 sepals and an inner whorl of 3 petals, one of which is usually larger
and showier. More importantly to the botanist, there is a fleshy,
club-shaped column projecting from the center of the flower that is a
fusion of the male and female reproductive organs. Orchids can be
divided roughly into two types; those that grow in the ground (usually
in temperate climates) and those that grow attached to rocks or trees
(in the tropics).
Orchids produce masses of tiny seeds
and a single pod can contain as
many as 4 million. You would think that with such numbers we would be
overrun with them, but each seed consists of an embryo of only 100-200
cells within a seed coat, and unlike most other seeds, it contains very
little stored food and must depend upon a special fungus to provide
nutrition. The fungal filaments penetrate the base end of the seed and
while the exact process seems to be poorly understood, it is thought
that the fungus digests organic materials and diffuses the resulting
nutrients into the cells of the orchid. The embryo then expands and
forms a tiny corm-like object that can germinate into a seedling, but
the process takes years to produce a flowering plant and is iffy at
best. In a few orchid species, chlorophyll never does develop, so they
must continue to rely on their associations with fungi for their food
all their lives.
In recent years, it has finally become
possible to grow most of the
native orchids from seed, a process that is allowing many more people
to have these lovely plants. Scott Weber, of Bluestem Farm at Baraboo,
plants the seed in agar, a gelatin-like product of a certain seaweed
that is enriched with nutrients, a procedure now used by all commercial
growers for both domestic and wild orchids. I now have several of his
showy lady slippers growing in the damp area of my wild garden where
they seem to be flourishing. The showy ladyslipper is the largest
native orchid in North America, and when in bloom, the white flower
with its delicate pink pouch is unmistakable.
In addition to the two lady slippers,
we have found other native
orchids growing on the farm. Rattlesnake plantain spreads its rosettes
of dark-green leaves netted with conspicuous white veins on the ground,
and in August, puts up 8-10 inch spikes with tiny 1/4" flowers in a
cylindrical arrangement near the top. The showy orchis has an
eight-inch stalk with purple and white blossoms, rising from two broad
leaves close to the ground. The twayblade is similar to the showy but
has more numerous flowers that are purple and brown with a wide
flattened lip. Puttyroot puts up a single pleated leaf that carries
over the winter and then sends up a bloom stalk the following summer,
and the coral root has no leaves at all and depends upon a fungus for
sustenance. We have also discovered several species of rein orchids,
tiny green plants that can easily be missed.
Some people insist that such precious
flowers should be left strictly
alone, but we have found that it is possible to increase their numbers
substantially by judicious husbandry, and we have been able to share
our bounty with many others. Hopefully, in this way, specimens of this
lovely wildflower now grace many areas where they had not previously
been growing.
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May 12, 2009: Look at all
the Bloomin' Trees!
In our enthusiasm for the early spring
wildflowers, we usually concentrate on the blossoms of bloodroot,
hepatica or trillium under foot, and often ignore the untold numbers of
other flowers above our heads. All trees bloom, else they could not
produce seeds, but most such flowers are overlooked because they are so
tiny they must be examined with a magnifying glass to see their
details.
Last summer, before each tree
completed its growth, it developed buds
on the tips of its twigs. These lay dormant throughout the winter but
now springtime’s longer periods of sunlight have stimulated their
growth. The first sign of activity is the expansion of the protective
scales that cover the bud as the underlying tissue begins to grow. Each
species has a particular number of scales: willow has a single scale;
basswood and some maples have a pair of dark red scales; and sugar
maples, beeches, birches, hornbeams, and oaks have multiple scales that
overlap like shingles.
Each species of tree has its own time
for blooming. Red maple is one of
the first, generally several weeks before the leaves appear. Many of
the small red flowers, clustered on twigs mostly in the upper portion
of the crown, are structurally perfect; that is, each has stamens that
produce pollen and a pistil that receives it for fertilization.
However, some trees are entirely male, producing no seeds, while others
are entirely female. Even on the trees that have both male and female
flowers, they are usually separated on different branches.
Elms also have perfect flowers, which
occur on drooping one-inch
stalks. They have no petals and look like little brown lumps about the
size of peppercorns, with tiny flecks of pollen sticking out; however,
if examined closely it can be seen that their inner parts are bright
red, light green, and green tinged with red. Even though elm flowers
are capable of pollinating themselves, the trees are essentially
self-sterile, as a Canadian test showed that seed from self-pollinated
flowers were only 1.5 percent viable.
Maple and elm flowers can afford to be
inconspicuous; because they are
wind-pollinated and so have no need to attract insects to do their
work. While it is true that the majority of flowering plants are
pollinated by insects, most trees have so many blossoms that they must
depend upon the wind, and usually produce great masses of pollen to
ensure that at least some of it reaches the right target. Since these
flowers do not need insects, they expend their energy in producing
pollen, not showy petals and sepals.
Oaks and hickories bloom shortly after
their leaves unfold, and they,
along with the poplars, birches, and willows, have peculiar male
flowers in the form of catkins. In early May, some cells at the end of
each oak twig swell into a vase-shaped organ topped with sticky knob
ready to capture any passing pollen grains. Other cells elongate and
swell into a drooping cluster of yellow balls, each ready to explode in
a cloud of pollen. Pollen and female flowers appear on an individual
tree at slightly different times, so that the flowers will not be
pollinated by the tree’s own pollen.
Black cherry is another tree that
leafs out before flowering. If you
carefully dissect one of its buds, you can see the embryonic leaves
looking like miniature versions of the mature ones, and often folded up
flowers as well. Its flowers, like those of the other fruit trees, have
petals and sepals, and are fragrant and laden with nectar to attract
bees and other insects that descend upon them in swarms.
Two other native fruit trees are much
smaller but have blossoms that
are quite noticeable in our woodlands, thickets, and along roadsides.
They both belong to the rose family, as do most fruit trees, and have
attractive and fragile flowers, with four or five petals. The wild plum
tree produces one-inch tart fruits that make delicious jams, but also
has sharp thorns along its branches. When mature it takes the form of a
shrub or small tree and usually grows from 10 to 20 feet in height. It
tends to form dense stands, and is common in the southern third of
Wisconsin. The tree has no special commercial value other than for its
fruit and wildlife value.
The other tree now in bloom is often
confused with the wild plum but
its flowers hang in loose clusters at the end of each twig and their
petals are long and narrow. It goes by a number of names but is most
often called serviceberry, Juneberry or shadbush. It too grows to about
15 feet in our woods, and while it usually appears here as a single
plant, it is said to spread by suckers into clumps like the wild plum.
Its fruit is more like a berry, however, and contains large seeds so
that we found it rather unsatisfactory to use in a pie. All kinds of
birds eat them with relish, however, and we are happy to leave the
fruit to them.
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May 5, 2009: Fantastic Fiddleheads
Lots of Wisconsinites are enthusiastic
morel mushroom hunters, and Bill
and I usually manage to find as many as we can eat, with surplus to
freeze for winter use. But there is another far less well-known wild
treat in the unlikely form of the fiddlehead
fern. Just like morels, fiddleheads are available in specialty stores
for only a few weeks in springtime and gourmet restaurants charge high
prices for them, but fiddleheads are also free for the picking. It is
wise to know what one is doing, however.
The fiddlehead is the unfurled frond
of a young fern that pushes up
through the ground in the early spring. It unrolls and lengthens as the
plant matures, a process that is the result of more growth in the
inside of the curl. It acquired its name because it resembles the
curled scroll on the end of a violin, (or more likely, early stringed
instrument makers copied the fern shape because of its beauty and then
applied the name).
Because of their commercial use, many
people mistakenly believe that
all fern fiddleheads are edible, but this is not the case and there are
numerous stories of people becoming sick from eating some. The safest
and most reliable species is the ostrich fern, Matteuccia
struthiopteris, found in northern regions across much of the world, and
particularly in the eastern half of North America. In Wisconsin it is
common throughout the state in wet forests and often in deep mucky
soils, and it sometimes forms extensive colonies.
The ostrich is a very large fern, with
fronds sometimes growing to five
feet, and it is easy to identify when mature. Its large, clumped fronds
taper toward their bases as well as their tips, and their shape as well
as its separate shorter lyre-shaped fertile fronds makes it
distinctive. Only the cinnamon fern is somewhat similar, but its fronds
are only slightly narrowed at the base.
The fiddleheads of other ferns such as
bracken, cinnamon, royal, and
sensitive are also gathered and eaten by some, but the Center for
Disease Control warns that these contain shikimic acid that can cause
illness in some people and animals. It is recommended that they be
cooked thoroughly in several waters before consumed, and since gourmet
cooks prefer to prepare fiddleheads by only a short steaming, this
overcooking ruins the vegetable for them. Our largest local fern, the
interrupted, is not considered edible at all, having a bitter taste and
a tendency to cause diarrhea.
Ferns have been with us for millions
of years and grow in many
different habitats around the world. Most are found in the tropics
where tree ferns have aboveground stems that may grow as high as 40
feet. The fossil record indicates that they once made up the great
majority of the vegetation, but later separated into two general
types--those that gave rise to flowering plants and others that evolved
into our modern ferns.
The frond is the part of the fern that
we see as we wander through the
woods, and is divided into two main parts, the leaf stalk and the blade
that may be finely cut or undivided. Its rhizomes are roughly
comparable to stems in the flowering plants, and in many cases are
inconspicuous or even entirely underground. The fronds arise from these
"stems" from the upper side or occur in one or more rows laterally on
each side. Roots are formed from the rhizomes and anchor the plant to
the ground and absorb water and minerals.
The fern has a complicated life style
that is called an alternation of
generations. The fertile frond has miniature sacks or capsules, usually
on its underside, that produce dust-like spores that are somewhat like
the seeds of a flowering plant. Ferns drop millions, often times
billions of spores during their lifetime but very few ever land in a
spot suitable for growth. These tiny single-celled organisms fall to
the ground, and those few that find suitable moisture and light undergo
cell division until they form little green heart shaped plantlets.
These plantlets, called prothallia,
usually go unnoticed as they are
only 1/2 inch or less across and lie flat on the ground. Despite their
size, these are independent organisms with root-like structures that
consist of single greatly-elongated cells that absorb water and mineral
salts and anchor the plant to the soil. Each grows female or male
organs on its underside which produce eggs and sperm, and if moisture
is plentiful, the sperm swim to the eggs and the fertilized eggs then
begin to develop into the plants that we recognize as ferns. It is
difficult to understand how such a strange process could have proved so
successful, but that is another of nature’s mysteries that confound us.
We enjoyed seeing so many of you at
our open houses the past two
weekends, and trust the plants you carried home will grow and prosper
in their new homes. This cool spring has retarded the growth of some of
our most beautiful flowers, however, so you are welcome to visit us in
the coming weeks and watch them as they bloom.
April 28, 2009: Woodcocks in Love
The American woodcock is a most
unusual bird. It is chunky,
short-legged, and short-tailed, and has a very long bill and very
large, dark eyes set high on the sides of its head, giving it an almost
360° field of view. It is superbly camouflaged and almost
impossible to see when crouched on the ground in the leaves, and only
becomes visible as night falls and it begins to call. The woodcock is a
shorebird that has transferred its habitat into the scrubland and
forest, but sometimes strays up into our hills in the springtime. It
breeds across eastern North America as far west as the Great Lakes, and
spends the winter in lowlands down along the Gulf Coast. We heard the
flutter of wings that is typical of its courting flight one evening
this last week and but could not spot the bird to be sure.
Woodcocks are usually found in damp
woods or older thickets, with moist
soil where earthworms, their favorite food, are easily found. Up to
ninety percent of their diet is made up of worms although they also
will eat beetles, flies, centipedes, and various insect larvae as well
as the seeds of some plants. There is some evidence that the woodcock
uses foot stomping and other body movements to locate underground prey.
It rocks its body back and forth without moving its head as it slowly
walks around, stepping heavily with its front foot. Then it pushes its
long bill into the soil, and if an earthworm moves beneath the surface,
the woodcock seems to be able to locate it, perhaps by feeling any
vibrations it causes. Unlike in most birds, the tip of the upper
mandible is flexible so that it can more easily grasp its prey.
Courtship usually begins in late
February, sometimes even on the
wintering grounds, and continues on the nesting ranges. The males are
always on the make and are no help with the family, and even the
females are casual mothers, often simply laying their four
grayish-orange eggs upon dry leaves. The young hatch in about three
weeks and are up and running within a few hours, but unlike many birds
that leave their nests at hatching, woodcock chicks cannot feed
themselves and are dependent on the mother for food. In three or four
days, however, they follow their mother’s example and begin to probe
the dirt themselves and are almost fully-grown in 28 days.
Years ago, our family always looked
forward to visiting a well-used
courting ground of a number of these birds. We would arrive as dusk
settled in and hide ourselves in secluded spots with good viewing. Soon
the distinctive call of the male (a nasal "peent") would sound, first
from one spot and then another. Then we would make out the bird
stalking in a circular pattern in its chosen site, and occasionally
catch a glimpse of a female crouched among the alder trunks. After a
minute or so, the male would jump into the air, spiraling up almost out
of sight. At the peak of its flight we would hear a unique twittering
sound created by the outer three wing primaries and then a melodic
warbling call. Then the bird would drop like a rock, often landing
within a few feet from where it had started and immediately resume its
“peenting”.
The woodcock population has declined
by about 1.2 percent each year
since the 1960s, possibly because of loss of habitat due to human
development or the maturing of the vegetation into mature forests, but
there are still plenty of these interesting birds around to put on
their spectacular spring performance. They seldom perform in our hills,
but friend Cindy has a farmette across from a low marshy area near Bear
Valley and tells us she hears them every evening.
One of our goals for the week is to
visit the area and see if we can
see any birds.
We drove by the local eagle aerie
south of Highway 60 a few days ago to
see if there was any activity and found the eagles were obviously
feeding at least two chicks. They were both standing in the huge nest,
hunched over and evidently poking food down ravenous gullets, but the
surprise was that close by were seven stick platforms that looked to be
heron nests. No birds were in evidence at the time and we conjectured
that the eagles may have harassed them until they stopped building and
moved elsewhere to a less threatening area, but we will be watching to
see if they return.
Great blues typically nest in treetops
close to lakes or other
wetlands, and build in rookeries that may contain as few as half a
dozen nests to as many as several hundred. They build bulky nests
constructed of large sticks, and the female lays three to six pale blue
eggs. It is the largest North American heron, with a head-to-tail
length of up to 55 inches, a wingspan of up to 80 inches, and a weight
of up to five pounds. Its primary food is small fish, though it is also
known to eat insects, rodents, amphibians, reptiles, and even small
birds. It uses its long legs to wade through shallow water, but will
also forage in fields especially around dawn and dusk. Herons locate
their food by sight and generally swallow it whole. It would be
exciting to have such a colony where they could be easily observed from
a road.
As I write this, it is the second day
of our wildflower sale, and rain
is continuing to fall. We really don’t need any more moisture, as it
fell steadily most of yesterday, leaving everything (including us and
the many customers who braved the weather) well watered. Hopefully, by
Saturday things will be sunny and warm, and we hope those of you who
did not visit us last weekend will come see the wildflowers and walk
the garden paths.
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April 21, 2009: A Warty Wonder
Anyone living within a short distance
of a body of water at this time
of year has to be aware of the tree frogs that have emerged from
hibernation and are enlivening the evenings and nighttime hours with
their calls. Several species live along the river but up here in the
hills we have only the spring peeper, a tiny creature that can make a
considerable racket for its size. Although it spends most of the year
out in the woods, all the peepers gather at the ponds for a big wild
party—perhaps I should say, orgy--in April. Their ear-splitting voices
and those of the barred owl pair that have set up housekeeping close by
are the only “songs” we hear at this point, but soon another amphibian
will be joining the chorus.
I was digging in the wild garden a few
days ago, gathering plants for
the wildflower sale, when the dirt moved and two eyes peered out at me
and blinked. A very sleepy toad had evidently spent the winter buried
there, and I was very relieved to find it still whole and unharmed by
my shovel. The toad has a mixed reputation; many children love it
because it is slow moving and easy to catch. It makes a congenial and
undemanding pet that will tolerate considerable neglect and has a
fascinating lifestyle that will play out right in the back yard if
there is a pond or even a persistent puddle. On the other hand,
many adult humans consider the toad to be a rather repugnant creepy
crawly, and even mistakenly think handling it will cause warts.
Toads and frogs are closely related,
but still noticeably different.
Toads usually have a dry, thick, bumpy skin and a squat body with
shorter legs. They are more likely to walk or hop and tend to live in
relatively dry habitat. Frogs have moist, smooth skin and slim bodies
with longer legs. They are more likely to leap or jump and usually live
in or near water. Both are amphibians, a classification that includes
those vertebrates that spend the juvenile stage of their lives
breathing under water with gills and then develop lungs to breathe air
as adults.
If you come upon a toad in the eastern
United States, it is most likely
an American toad. This species is very common, and even though it is
nocturnal and hides much of the time, most people are quite familiar
with it. During daylight hours it seeks cover beneath a porch, under a
flat stone, log, woodpile, or other cover, but at dusk, it emerges to
feed. Insects, spiders, earthworms, snails, and slugs make up most of
its diet, but it will eat just about anything that moves and will fit
into its mouth. The tongue is attached to the front of its mouth and
its sticky tip is flicked forward to grasp the prey and carry it back
into the maw. If the prey is large, the toad will use its “hands” to
stuff it in.
The female toad can grow to four
inches in length, although the male is
considerably smaller. Both are usually very fat, and have gold speckled
eyes and short snouts on their outsized heads. They have large, dark
spots on their backs, each containing one or two "warts" that are
actually bumpy skin glands. Toads also have enlarged, kidney-shaped
bumps called the paratoid glands, one behind each eye on the side of
the neck, that secrete a viscous white poison that gets in the mouth of
any would-be predator, and usually causes extreme discomfort. (To get
around these paratoid glands, raccoons will flip a toad over and eat
from the underside). Other defenses include playing dead and puffing up
their bodies to look bigger than they actually are.
During the colder winter months a toad
will burrow deep into the
ground. When digging, it backs in, pushing out dirt with its hind legs.
Once it is deep enough, it enters into torpor, a short-term state of
decreased physiological activity, until spring. With the arrival of
warmer weather, the males emerge and travel to water where they begin
calling to attract females and announce their presence to other males.
To produce the sound, males inflate the round, mottled gray vocal sacs
on their throats and create long, drawn-out, high-pitched, musical
trills lasting up to 30 seconds. The female toads are attracted to the
singing males and breeding takes place.
Toad eggs are laid in water in long
double strings of several thousand
eggs each and encased in clear gel. Tiny black tadpoles hatch in 3 to
12 days, depending upon the water temperature, and swim in schools and
feed on plants and debris. In about two months, the tadpoles have grown
legs, reabsorbed their tails, changed from gill-breathing to
lung-breathing, and begun to eat insects rather than plant material. At
this point they emerge onto the land, although it is two to three years
before they mature and can reproduce.
I don’t know if the toads will be
singing at the wildflower open house
this and next weekend, but I think it is likely that at least a few
spring peepers will. Come and visit the wild garden and see the early
flowers, as well as the variety of creatures make it their home. We
will be looking for you.
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April 14, 2009: What's With the Easter
Bunny?
Now that the Easter bunny has come and
gone, perhaps we might take a
closer look at this time-honored institution. For some children, the
arrival of the famous rabbit ranks up there as almost as important an
event as the visit of Santa Claus. Both myths seem to have had their
origins in Europe, but the first Santa is reported to have been a real
person, Saint Nicholas of Myra, a 4th-century bishop who was famous for
his generous gifts to the poor. How the tradition of the Easter bunny
arose is a bit more obscure, but this Easter symbol was first mentioned
in German writings in the 1600s. Children would set out nests, often
made up from their caps and bonnets, and if they had been good, the
“Oschterhas” would lay brightly colored eggs in the nest.
(Ēostra
was a pagan goddess whose name survives in the modern holiday name
Easter, and "Hase" means "hare", not rabbit, as the "Easter Bunny" is a
hare in old legends.)
It probably should not surprise us
that the activities of hares and
rabbits should be incorporated into Easter folklore as they had been
connected to springtime productivity throughout history. They are both
prolific breeders, maturing at an early age, and giving birth to
several litters a year. Eggs also have been fertility symbols, but how
the stories of rabbits laying eggs came about is not really known. It
is guessed that perhaps the fact that baby hares were found in hollows
in the grass that looked quite similar to nearby birds’ nests
containing eggs might have given rise to the belief.
In North America, the common
cottontail rabbit displaced the European
hare as the Easter bunny. Cottontails have always been plentiful in
Wisconsin, but they extended their range and increased in numbers as
farmers pushed westward. The state population today remains fairly
stable at over five million, with the great majority in the southern
two-thirds of the state and near urban areas.
Female cottontails give birth to 3-6
young, and can have two or three
litters per year, mating again almost immediately. Young cottontails
are born naked, blind, and almost totally helpless, and their mother
visits them only to nurse. By two weeks, they can play and forage
outside the nest, and at four to five weeks, they are weaned and
independent. They have sharp incisor teeth that grow continuously, and
make a characteristic diagonal, 45º cut when clipping off woody
twigs, buds from saplings, or flower heads. (Deer have no upper front
teeth and must twist and pull when browsing, leaving a ragged break on
the twig, so it is easy to tell the culprit when something has been
wreaking havoc on your garden.)
Besides the cottontail, we have two
hares in Wisconsin—the snowshoe
hare and the white-tailed jackrabbit. In general, hares are bigger than
cottontails, have longer ears, very large hind feet, and longer legs
made for jumping and for standing up to reach twigs and branches.
Snowshoe hares are not found in the southern parts of the state, but it
is possible to see an occasional white-tailed jackrabbit. It is
larger than a cottontail, weighting as much as ten pounds, and has ears
some eight inches in length. In contrast to the cottontail, it is born
with fur and has its eyes open. After about 15 days, the young hare is
weaned and within two months it is completely independent. It is not
known if jackrabbits were native to Wisconsin but in the late 1800s
there was widespread stocking for hunting purposes. In the mid 20th
century the population peaked between 50,000 and 75,000 hares, but
since that time, their numbers have declined considerably, mostly it is
thought due to habitat loss.
The white-tailed jackrabbit is a
loner, but small populations live in
open areas throughout central and southern Wisconsin. Camouflage is the
hare's main defense against predators, and often it will lay on the
ground, with ears flat against its body, and not move unless closely
approached. Jacks begin mating about mid-April and females give birth
to 2-6 young. They make no real nest or shelter for their young, and
instead may drop them onto bare ground or in a scratched-out resting
place. In the summer, this hare is brownish gray, but during the
winter, the coat is snowy white, with only the ears being tipped in
black.
Both rabbits and hares are quite
capable of causing considerable damage
to our garden flowers and vegetables during the summer as well as young
trees and shrubs plantings when snow covers their other food; still,
they themselves are a major source of food for many of our predators.
The big owls, hawks, eagles, coyotes, foxes, badgers, wolves, and wild
cats can and do prey upon the adults, and numerous smaller birds and
animals take most of the young. This is most fortunate as it normally
balances out their prolific breeding so that we are not often
overrun.
Baby bunnies are not the only arrivals
in late April, as this is also
spring wildflower time. We invite you to visit us at Timbergreen Farm
on Saturday April 25-26th and May 2-3, to explore the trails and
perhaps purchase some of the potted native wildflowers that will be for
sale. The yellow lady slippers have always been a hot item and this
year we will be offering a few on each Saturday in an effort to give
more people a chance to obtain one of these exquisite flowers. Catt,
Cindy, and I will be on hand to try to answer any questions you might
have, so come see us.
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April 7, 2009: Consider the Egg
You would think that any reasonable
flycatcher would remain at its
winter refuge until it is warm enough in Wisconsin for the insects to
emerge, but eastern phoebes have their own schedule and that seems to
tell them it is time to set up housekeeping. Of course, this particular
bird (or one of its relatives) has never shown much sense along these
lines as it has often chosen to build under the eaves of the little
stone building that we use as our headquarters for the wildflower sales
and directly over the door at that. Anyone entering or exiting the
building must pass within inches of the nest, sending the brooding bird
scurrying off to a nearby tree in a tizzy. The last couple of years it
did move around to the back of the shed, but now it has returned and I
am considering if I should try to convince it to do otherwise. While a
phoebe will build her nest on a rock ledge or in a cave, she much
prefers man-made structures, locating her nest on a building rafter, on
a windowsill, or on a bridge girder.
The eastern phoebe sports gray-brown
feathers above and whitish ones
below with no eye rings and wing bars to distinguish it. Still, its
habit of tail bobbing and wagging is a much more obvious characteristic
than its non-descript plumage and makes identification easy. It gets
its name from its distinctive two-note raspy call, and holds the
distinction of being the subject of the first bird banding experiment
in North America. In the early 1800’s, John Audubon tied thin silver
wires on the legs of a brood of eastern phoebes and was delighted to
discover that they returned to breed in the same area the following
year.
Early as it is, the phoebe is not the
first local bird to ready its
nest. The great horned owl has been known to lay its first egg late in
January in Wisconsin, and last year actually set a new early egg laying
record at its Oak Creek Power Plant nest site on January 8, where a web
cam recorded the event. The bald eagle is not far behind and often
begins to refurbish its nest in February and lays its eggs soon after,
as the young of the big predatory birds need long months of growth and
gaining experience in hunting before the lean months of winter overtake
them. Even our little kestrel is evidently sitting on eggs. These small
falcons have been using one of the ventilator holes in our barn for a
number of years now, and we have been watching them coming and going
for several weeks.
The creation of a bird egg is a
marvelous process. After mating, sperm
swim up the oviduct inside the female to the ovum, located in the white
spot that is found on top of the yolk. After fertilization, the ovum
with its yolk begins its journey down the oviduct, a passage lasting
about 24 hours. During the first three or four hours, moving at about
one tenth of an inch per minute, albumen (egg white) is added around
the ovum and its yolk, and membranes are then applied to support and
protect them. Finally the shell is deposited, a procedure that takes
another 19 to 20 hours. The shell is mostly composed of calcium
carbonate, which has the same chemical formula as limestone. The shell
of a bird's egg is often colored or patterned to help camouflage it
from predators, an important detail for birds which nest on the ground.
Whether the female lays two or twenty
eggs in her clutch, she can only
lay one egg per day. This is important because birds' eggs are
relatively large in comparison to the bird. She usually lays her egg
early in the morning so that she can be unencumbered in her hunt for
food the rest of the day. Most bird eggs have an oval shape, with one
end rounded and the other more pointed. This shape results from the egg
being pushed through the oviduct while it is still malleable, and the
pointy end develops at the back. Cliff-nesting birds often have highly
conical eggs, presumably so that they are less likely to roll off since
they tend instead to roll around in a tight circle. In contrast, many
hole-nesting birds have nearly spherical eggs.
Birds must take great care of their
eggs. Usually the eggs are laid in
a nest, which may be a simple scrape on the ground or a very elaborate
construction high in a treetop. Whatever the setting, once the embryo
begins to grow it must be kept uniformly warm to develop normally. The
heat is supplied from the body of the female (and sometimes by the
male) insulated with lots of downy feathers. Both the albumen and yolk
will serve as food material for the developing chick, and after about
two weeks, most of our songbirds are ready to hatch. At this point,
each is little more than a huge mouth attached to a bulging stomach,
but in another two weeks the chick will have sprouted feathers and be
ready to leave the nest. Grouse, turkeys, ducks, cranes, and geese
remain in the egg for three weeks and longer, and the hatching chicks
are capable of running around and feeding themselves as soon as they
emerge. These females will not begin brooding their eggs until the last
egg has been laid so that all hatch within a day or so and can be
tended as a group. What an amazing process!
March 31, 2009: Butterflies in March?
There is nothing like a Wisconsin
winter to make one appreciate warm
sunny weather, and although such days have been few and far between,
when they do come, we are not the only creatures to take advantage of
them. Last week, perhaps the most surprising sight was that of mourning
cloak butterflies fluttering about the farmyard and along the trails in
the woods. Where did they come from and what are they finding to eat?
The mourning cloak presumably received
its name from the dark maroon
color of its upper wing surfaces which reminded early observers of the
outer garments that were once worn by persons in mourning. Thankfully,
the somberness is relieved by a bright yellow border on each wing and a
darker inner band that is decorated with bright blue spots. The outer
wing surfaces are marked with spots and irregular patterns colored in
earth tones, and the outline of the wings is zagged, both serving as
camouflage when the insect is hiding.
Mourning cloaks belong to one of the
larger Lepidoptera families, the
brush-footed butterflies, identified by the strange characteristic that
they seem to have only four legs, in contrast to the general rule of
six legs for insects. This is because the front pair of legs is reduced
and held tightly to the body, and appear to be hairy and
"brush-like"—hence the name. The larvae tend to feed side by side on
tree leaves--generally willow. poplar, elm, or birch--and are black and
spiny, with a row of red spots running down the back. Our family
observed this process one year in Madison when dozens of the
caterpillars appeared on our patio after having fed in an overhanging
elm. We gathered them up into a box, watched them hang upside down from
the provided branches, and split their skins. They were so close to
each other that their shedding gyrations punctured their neighbors, but
this did not seem to do any permanent damage. We watched the
chrysalises for three weeks, and were thrilled when the beautiful
adults insects emerged and spread their wings. I piled the whole bunch
into the station wagon and drove them out to the country to prevent
being inundated by the next generation, however.
The adult butterfly will drink nectar
but prefers tree sap to build up
fat stores for hibernation. When freezing weather approaches, water is
gradually extracted from its body cells and special antifreeze proteins
are produced and circulated in the blood, which act to prevent any tiny
ice crystals from growing and damaging tissues. The insect also builds
up extremely high concentrations of sugars or sugar alcohols in its
blood and tissues to lower the freezing point of its body water. By
midwinter, the amount of glycerol is so high that it often makes up
20-25% of its entire body weight! When the insect thaws, the process is
reversed, the cells re-hydrate, and it can resume activity once the
temperature is warm enough to allow movement, although it will become
dormant again if the cold returns.
Mourning cloaks are not the only
butterflies out and about these March
and April days, as a number of its cousins have also been hibernating
nearby. Both the Compton and Milbert’s tortoiseshells are common in
this area, the 2 ½ inch Compton having the typical brush-footed
characteristics but with lovely black and orange-brown colors, and the
smaller Milbert’s being brown with orange borders on its wings. A
Compton visited the barnyard a few days ago, but I think it and the
mourning cloaks have retreated to their hideouts until the weather
settles down.
Another butterfly that flies almost as
soon as the brush-footed group
is the spring azure, a tiny one-inch insect that over-winters in its
chrysalis. It can sometimes be seen when patches of snow are still
present, but more typically appears about the time the very first
flowers open. This species presents a complex set of identities to
entomologists as genetic and biological evidence suggests several
distinct butterflies still remain under that name. A darker, bluer,
highly variable first brood produces chrysalises that may over-winter
or emerge the same year. Chrysalises from the first of the paler, late
spring and summer broods will hatch several weeks later, with the last
ones of later summer over-wintering. The caterpillars of different
broods feed on different plants depending upon what is flowering at the
time.
Other butterflies that spend the
winter in their pupal stage are the
swallowtails, although most of them wait until May to emerge. They are
called swallowtails because they have long "tails" on their hind-wings
which look a bit like a bird’s long, pointed tail. Their caterpillars
are also unique in having a bright orange fleshy forked organ called an
osmetrium that they stick out from behind their head when disturbed to
scare off predators. (Osmetria give off a bad smell.) Our two common
swallowtail butterflies are the tiger swallowtail, a strong flier with
distinctive yellow and black striped markings on its wings and body
(some females are brown or black) and the black, whose upper surfaces
of the wings are mostly black. The giant swallowtail, the biggest of
them all with bright yellow spots on its black wings, is a migrant and
does not seem to winter in Wisconsin, although we enjoy its presence
all summer long.
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March 24, 2009: What in the
World is a Syrinx?
The first thing you might notice when
you step out for an early morning
listen is the great variety of sounds produced by the singing birds.
The redwing has little more than a “cha-reeeeeeeee” while the cardinal
gives forth with “cheer-cheer-cheer-purty-purty-purty“. The song
sparrow sings, “Hip; hip; hip hurrah boys; spring is here!” with its
three similar introductory notes, while the bluebird, which seems as if
it should have a lovely melody, comes out with a muffled twitter.
Scientists tell us that birds produce five basic types of sound: call,
song, territorial, fledgling, and alarm. The first four are used during
their daily life and work, while the alarm notes are agitated and warn
of a threat. Within each of these basic types, the particular of
meanings of these sounds are based upon inflection, body language and
background setting.
Most song is produced by the male bird
and is usually delivered from a
prominent perch adjacent to its nesting area. Songs are often longer
and more complex than calls, and are usually associated with courtship
and mating. Strangely, some species are nearly voiceless, but non-vocal
sounds such as the drumming of woodpeckers and the "winnowing" of
snipes’ wings in display flight are also considered songs. A female
often seems to choose the male with the most impressive “song” as her
mate, and experiments suggest that the quality of each bird’s song
could be a good indicator of fitness. This may be because parasites and
disease will affect the male’s song, or just because ability of a male
bird to hold and advertise a good territory demonstrates his health.
We tend to think that birdsong is
whistling, and we know that when we
whistle, we produce that sound in the mouth. However, many of us with a
farm background who have seen a chicken’s head cut off might have heard
it continue to squawk as it flops headless on the ground. It can do
this because the sound doesn't come from the head but from its body; in
fact, birds have a song-making organ that other animals, including
humans, do not, called the syrinx.
When air enters a bird's nostrils and
mouth, it flows through the
trachea to the lungs, as is the case with most higher animals. The
bird's syrinx is shaped like an upside-down, hollow “Y” and is located
where the trachea forks, with one branch leading toward each lung. If a
bird wants to sing or squawk, it tightens up its syrinx muscles so that
air moving through it is pressurized and causes a membrane inside to
vibrate, creating sound. The bird can control the pitch by changing the
tension on the membrane and both pitch and volume by the amount of air
that passes over it. It can also control the two sides of the trachea
independently, allowing some species to produce two notes at once.
When a male bird is raised in
isolation, it still sings, but its song
sounds distinctly different from others of its species. It appears that
although the basic song is the same for all of the same type, young
birds learn details of their songs from their fathers, and these
variations build up over generations to form dialects. Zebra finches,
the most popular species for birdsong research, have been observed to
develop a version of the adult's song only three weeks from hatching,
but it requires two to three months for the young bird to perfect its
final version.
The language of birds has long been a
topic for study, and it is
obvious to all that most calls have meanings that are understood by
other birds. Many species can even imitate human speech or other
sounds, and a study by Irene Pepperberg, professor of psychology at
Brandeis University and lecturer at Harvard University noted for her
studies in animal cognition, suggested that some birds demonstrate
considerable learning ability. She trained an African grey parrot named
Alex to use words to answer complex questions such as "How many red
squares?" with over 80% accuracy. It was trained by using two teachers,
one to give instructions, and the other to act as a model who would
give the correct response. The bird copied the model’s answers and was
able to identify objects by color, shape, and number at about the level
of a chimpanzee or dolphin. Critics cited the “Clever Hans effect”
(named for a horse who seemed to be able to count and do other
intellectual tasks but was later proved to be receiving cues from the
body language of the human trainer), but Pepperberg countered that her
controls and tests made it impossible for Alex simply to recite words
when she asked questions.
Such research has not been conducted
with our local birds, but
evidences of their intelligence keep popping up. Crows have been known
to steal fish from ice fishermen by using their beaks and feet to pull
up the lines when the men were not looking, and, in experiments, jays
have been shown to remember exactly where they hid acorns. In one study
jays were able to find seeds almost a year after they hid them and it
was thought that they remembered these by forming and storing detailed
image maps of the surrounding area. Other species may not be as clever,
but each has its own song, and these are so distinctive that many
birders routinely identify a bird solely by its sound. The next two
months will be prime listening as all the birds set up housekeeping and
raise their young. Enjoy the chorus.
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March 17, 2009: The Mystery of
Maple Sap
No one is sure just how long people have been collecting the sap from
maple trees in North America, but legend hints that maple syrup and
maple sugar were being made well before recorded history. Some
historians maintain that Native Americans did not have the technology
or tools to perform the necessary boiling of sap to make either
product, but others believe that early peoples had discovered that they
could use a sharp tool to make incisions in the tree bark, and then
could insert a hollow reed or concave piece of bark into the hole to
obtain the sap.
Eventually they must have found it
possible to collect the sap into
containers made from birch bark or animal skin, and later into clay
pots. Such liquid would have been a treasured commodity for its
sweetness, and also as a drink when water was scarce. It is thought
that collectors might have learned to concentrate the sap somewhat
either by adding hot stones or else by repeatedly allowing it to freeze
overnight and disposing of any ice that had formed on top, but with the
development of clay pots, these less-than-efficient methods would have
been replaced by boiling.
The first white settlers and fur
traders introduced wooden buckets to
the process, as well as iron and copper kettles, and during the 17th
and 18th centuries, the syrup was a major source of high quality pure
sugar. Later, they would learn to bore holes in the trees and hang
their buckets on spouts, but since it required some 40 gallons of sap
to obtain a gallon of maple syrup and the process required careful
tending over an open fire to avoid burning, it always was a major
undertaking. A single tap can produce about 10 gallons of sap each year
and yield approximately one quart of finished syrup.
There have been a number of theories
on the mechanics of this
out-flowing of maple sap through the years, but only recently has the
process been adequately explained. All that was obvious up to now was
that sap flow was definitely temperature dependent, and required
freezing temperatures at night followed by sunny above-freezing days.
The Massachusetts Maple Association
tells it this way: A rise in
temperature of the sapwood to above 32 degrees F. causes a positive
pressure within the wood that produces the sap flow. Many people assume
that maple sap flows up from the tree's roots on warm days. Actually,
on warm spring days the internal pressure of the tree causes the sap to
flow out, much the same way blood flows out of a cut. The exact
mechanism of this pressure is not completely understood, although
several hypotheses have been advanced and individual trees differ in
the rate of response to temperature. When the temperature falls to
near, or below freezing, the pressure may become negative in relation
to atmospheric pressure. As the maple tree begins to freeze, sap is
actually sucked up into the tree through the large wood pores that
connect with the tree's roots so that the tree is actually recharging
itself with liquid from its roots. Unfortunately, even this explanation
does not make much sense when one considers that water expands as it
freezes. If this is true, the trees ought to push out sap when they
freeze and suck it up when they thaw. This is the case for most
hardwood species; however, maples suck sap as they freeze and drip sap
when they thaw.
Scientists at Cornell University at
Ithaca NY now add this further
explanation: Sap flows through cells in the sapwood, which is the
relatively thin, youngest, outer part of the woody stem of a tree.
These cells act as pipes to transport water and dissolved materials
from the roots to the branches of the tree and back again. During the
day, activity in the cells of the sapwood produces carbon dioxide that
is released into both the intercellular spaces in the sapwood as well
as into the spaces between the cells, causing pressure to build up in
the cells. A third source of pressure is called osmotic pressure, which
is caused by the presence of sugar and other substances dissolved in
the sap. When a hole is made through the bark of the tree, the pressure
forces the sap out, but when temperatures go below freezing, the carbon
dioxide cools and therefore contracts, as does the cooled sap. This
creates suction in the tree that causes water from the soil to be drawn
up into the roots and travel up through the sapwood, ready to flow
again when the temperatures rise.
March brings us other signs of spring
besides rising sap. The sandhill
cranes have returned to the marshes, redwings are calling from our
treetops, and bluebirds are singing on sunny days on the wires above
the houses along the road. Any snow which falls these days will be
short-lived and in the next few weeks, our winter birds will be leaving
us for their nesting grounds up North, to be replaced by old friends
who have been on vacation to the south. Can there be a more exciting
time of the year?
March 3, 2009: Too Much of a
Good Thing
Many a story has begun with the
nostalgic description of a formation of
Canada geese flying overhead—either as a portent of autumn, or as a
promise of spring after a bitter winter. Forty years ago, when we first
began to explore Wisconsin’s wild places, we too looked forward to
these sightings, as geese that nested far to the north migrated back
and forth from warmer climes. We could hear them long before we could
see them, and would scan the sky, looking for the distinctive “V”
pattern that would often be formed by dozens of the big birds.
Canada Geese are waterfowl that live
throughout most of North America
and are easily identified by their long black necks and heads with
contrasting white cheeks and throat areas. They historically eat
aquatic vegetation, and prefer to live around ponds, river and
lakeshores, but with available crop fields, many have expanded their
ranges and habitats. Usually they will spend up to 12 hours a day
feeding to take in the 4 pounds of grasses, roots, leaves that they
need.
Biologists have identified eleven
subspecies, the largest being the
giant, with a wingspan of 6 feet and weighing up to 20 pounds, down to
the smallest, the so-called "cackling" goose, which weighs only 2-4
pounds. Most nest from southern Canada up to the high Arctic tundra,
and travel long distances in their annual migration, but the giant
Canada goose is native to the Great Plains and is unique in usually
being non-migratory. This group was considered virtually extinct half a
century ago because of over-hunting and destruction of wetlands, but
then a few remnant populations were discovered, and with improved game
management practices and extensive re-introduction programs their
numbers have increased until they have become a nuisance at best and
reportedly sometimes a serious threat.
The ditching of the Airbus A320
several weeks ago was a case in point.
The reason for that accident was a collision with geese that were
sucked into both engines at takeoff, causing complete loss of power.
Current regulations on such engines by the Federal Aviation
Administration state that they must only be able to withstand the
impact of a 4-pound bird, far smaller than a typical Canada goose, and
John Ostrom, chairman of the Bird Strike Committee in Minneapolis, an
independent panel of aviation and wildlife experts, reports that
concern had been building about the possibility such an accident.
Unfortunately, wildlife is attracted to the relatively undisturbed
buffer zones around airports that are often wetlands with good nesting
areas. According to the U.S. Department of Agriculture's Wildlife
Services, there were 82,057 reported plane/bird strikes between 1999
and 2007, with 7,439 in 2007 alone. Federal Aviation Administration
officials, however, emphasized that the loss of two engines made the
ditching of Flight 1549 an extraordinarily rare event.
These geese have not only become a
common sight around many airports,
but also have appeared in many city parks, raising health questions. An
adult goose drops about 2 pounds of fecal matter each day and this
accumulation has been linked to the spread of diseases and bacterial
infections, although I should mention that Dr. Milton Friend, U.S. Fish
and Wildlife Service Waterfowl Infectious Disease Specialist, states
that this material does not significantly threaten public health.
There is no denying that large concentrations of the big birds do
cause unsightly conditions, however.
Part of the problem is that the giant
geese have proved to be very
adaptable and will even nest in urban settings if water is nearby.
There they are relatively safe from predation and may live up to 20
years and more. They mate for life, and are dutiful and devoted
parents. As soon as water is open for their courting rituals, they will
construct their elaborate nests of grass and cattail stems and rear
their 5-7 goslings.
Canada geese are very social and vocal
creatures, and scientists
believe that they make as many as 13 different sounds for greeting,
warning and contentment. The gander has a low-pitched "honk" while the
goose's voice is a much quicker and higher-pitched "hink". These
calls become frantic when the birds are feeling threatened or excited,
and when a flock gets ready to take flight, they create a raucous
chorus. The Canada goose may be one of the most talkative animals after
the human, and goslings begin to communicate with their parents while
still in the egg.
Efforts have been made to reduce the
over-population of these giant
geese in both the United States and Canada by a wide variety of means.
In some areas, they have been rounded up and killed, in others, their
eggs rendered infertile. Trained dogs have been enlisted and loud
noises broadcast to harass them. Canada geese supporters point out that
the giant geese flourish best on pampered mowed lawns and that simply
allowing areas where they congregate to grow “wild” will discourage
their presence. They also contend that banning all feeding would be a
big help in dispersing the birds. Research is ongoing and hopefully
ways can be found to limit their propagation without the wholesale
eradication that is being carried out in some areas and considered in
many others.
----------------------------------------------------
February 25, 2009: A Squirrel by Any
Other Name...
Years ago an author for the Saturday
Evening Post gave unforgettable
faux Germanic names to creatures in his articles. One that we have
always enjoyed was “nutsengehiden tailenflicker” a name that left
little doubt as to what he was referring, and others were just as apt.
The official but sometimes strange-seeming monikers of many of our
plants and animals are just as descriptive—only in Latin. Usually, a
species is called by its genus name that is always capitalized,
followed by its species name in lower case, so a human being is called
Homo sapiens. In Latin that means "wise man."
In scientific literature, all living
things are divided into five
kingdoms: Animalia, which is made up of (what else?) animals; Plantae,
which is made up of plants; Protista, which is made up of single-celled
creatures invisible to the human eye; Fungi, which is made up of
mushrooms, mold, yeast, lichen, etc; and Monera, which is made up of
the three types of bacteria. Each of these kingdoms is broken down into
phyla; for instance, in the animal kingdom, the best-known phylum is
Chordata, which contains all the animals with nerve chords and
backbones. This in turn is divided into classes such as Aves (birds),
Reptilia, Amphibia, Mammalia, and several others. Mammalia can be
broken down further into orders; Rodentia (mice, rats), Primates (apes,
monkeys, man), Chiroptera (bats), Insectivora (shrews, moles),
Carnivora (dogs, cats, weasels), Perissodactyla (horses, zebras),
Artiodactyla (cows), Proboscidea (elephants) and many more.
How did they get these names? Rodentia
comes from the word for gnawing,
and all rodents have a pair of prominent upper and lower teeth.
Carnivora means “meat eating” and the animals are distinguished by
their sharp canine teeth. Chiroptera translates into "hand wing” and
includes animals who have wings are formed by a stretched membrane
across elongated finger bones to the sides of the body and all the way
down enclosing the legs and tail. Ungulata means “hoofed” such as deer,
while Perissodactyla (odd-toed ungulates) are those that bear their
weight on the longer middle digit on each foot, such as horses. Then
there is the Proboscidea, which literally means "eat with the nose”,
and of course includes the elephant whose trunk is able to pick up the
smallest of objects and put them into its mouth.
But let’s return to the
tailenflicker—the gray squirrel. It is
officially Animalia: Chordata: Mammalia: Rodentia: Sciuridae (the name
means "shade-tail," and refers to its bushy tail); Sciurus carolinensis
(refers to the Carolinas, where the species was first recorded). Gray
squirrels come in many colors. Shades of gray are the most common
followed by brown, but also pure white and black. The common red
squirrel can also have an all black coat, but it is usually found only
in coniferous forests. In the summer squirrels are most active two to
three hours after sunrise, resuming activity again two hours before
sunset. The squirrel will retire to its nest well before dark, and will
rarely stir during the night. Throughout winter storms, or in severe
cold, the squirrel may not leave the nest for days.
The gray and fox squirrels are very
active at this time of the year,
with the males chasing through the trees at top speed, performing
almost unbelievable acrobatics. These are to impress any nearby females
and also to pursue any other males who enter their territories. A
female squirrel will choose what she believes is the strongest male,
and after a gestation period of about 60 days will produce a litter of
three or four babies, called drays by some sources although others use
the term for the whole litter. Each weighs about an ounce at birth, and
is only one inch long. They do not have hair or teeth, and are
virtually blind for the first six to eight weeks.
The gray squirrel’s diet consists of
nuts, seeds and fruit and the
average adult needs to eat about a pound of food a week. It will also
raid bird nests for eggs or nestlings, eat bugs, and even carrion if
really hungry. A squirrel will break the shell of a nut with its teeth,
then clean it by licking or rubbing it, before burying any surplus.
Handling it applies a scent to the nut from sweat glands between its
toes that helps the squirrel find it later, even under a foot of snow.
An adult squirrel's brain is about the
size of a walnut, and its eyes
are located high on each side of the head, allowing a wide field of
vision. It communicates through a series of chirps, and the frequency
and the duration of the notes can convey anything from pleasure to
alarm. These sounds plus vigorous tail flicks form the basis for almost
all squirrel communication.
A squirrel’s incisors grow continuously
and would soon outgrow its mouth if it did not wear them down by
constantly chewing on branches and twigs. They also have been known to
cause considerable damage to structures and even power lines with these
sharp teeth.
The squirrels are not the only
creatures that are recognizing the
changing of the season. The cardinals are singing and a neighbor heard
a ruffed grouse drumming. A flock of bluebirds flew in front of us as
we walked the road, and the coyotes have been very vocal the last
couple of nights. All of these are promising signs that spring is just
around the corner, despite any snowstorms to the contrary.
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February 17, 2009: An "Opassom?"
One of the strangest animals on the
continent lives right near our own
back yards. Although it looks something like a big fat rat, the
Virginia opossum is North America’s only marsupial (pouched mammal) and
is related to the kangaroo and koala. The female gives birth twice a
year and this alone is the subject of numerous scientific papers, as
her embryos spend their first 10 days of existence in eggs that float
in her uterus. At this point, as I understand it, the shell membranes
disintegrate and the yolk sacs make contact with the uterine wall,
passing nutrients directly into the embryos. After several days,
however, this transfer becomes inadequate and they must be born.
An average litter consists of 10
infants, (although it might be as high
as 20) and they are so small that all 10 could fit into a teaspoon.
Each weighs only 1/200 of an ounce and lacks fully developed hind
limbs, but it must make the long and difficult journey from the birth
canal into its mother’s pouch. The mother helps by licking her belly
hair, providing a moist path for the infants to follow, and once there,
each must latch onto a teat that then swells inside its mouth, locking
it in place. There are 13 teats and any excess babies die. Those who
are successful remain in the pouch for about ten weeks, eventually
pushing each other out to cling to their mother's back.
An early description of the opossum
comes from explorer John Smith, who
wrote in Map of Virginia, with a Description of the Countrey, the
Commodities, People, Government and Religion in 1608, that "An Opassom
hath an head like a Swine, and a taile like a Rat, and is of the bignes
of a Cat. Under her belly she hath a bagge, wherein she lodgeth,
carrieth, and sucketh her young." It is thought that he was the first
to give it its name, a word that was adopted from the Algonquin
'apasum', which means 'white animal. Originally native to the eastern
United States, the Virginia opossum was introduced into the West during
the depression years, probably as a source of food, and its range has
been expanding steadily northwards.
It was once commonly believed that
marsupials were a primitive
forerunner of modern placental mammals, but fossil evidence, first
presented by researcher M.J. Spechtt in 1982, suggests that by 110
million years ago, mammals had diverged into two distinct groups, the
placentals (a group that includes most modern mammals) and the
marsupials. He determined that fossil marsupials could be distinguished
by their teeth -- marsupials have 3 premolars and 4 molars whilst
placentals have 3-5 premolars and 3 molars. Following these clues it is
thought that the opossum already lived during the age of dinosaurs, as
fossil remains have been found from 70 million years ago.
Learning and discrimination tests rank
the opossum above the dog in
intelligence and more on the level of a pig. It has grayish fur
everywhere but on its ears, feet and tail. It has a pointed nose and
naked prehensile (grasping) tail that it uses as a brace and a fifth
limb when climbing, and also to carry bunches of leaves or bedding
materials to its nest. The tail is not strong enough to support an
adult’s hanging weight as folklore would have it, but babies have been
observed dangling briefly. In addition, the tail acts as a repository
for extra fat reserves, enabling the animal to survive lean times. The
opossum also has two opposable thumb-like digits on its rear feet that
help it grasp branches when it climbs.
Opossums have a naturally high level
of immunity to diseases and are
more resistant to rabies than any other mammal. One is about eight
times less likely to carry rabies than a wild canine, and only about
one in eight hundred is infected with this virus. Some even show
partial or total immunity to the venom of rattlesnakes.
If threatened, an opossum will put up
a terrific bluff with sharp teeth
and growls, but then often will collapse and "play possum". This
involuntary response causes the animal to become comatose for an hour
or two, mimicking the appearance and smell of a dead animal. The lips
are drawn back, teeth are bared, saliva foams around the mouth, and a
foul-smelling fluid is secreted from the anal glands. Its can be
prodded, turned over, and even carried away without a response, but
after a short period the animal will regain consciousness and amble
off. Few opossums survive to adulthood, however, and those that do have
a life expectancy of only from one to two years. The opossum was once
hunted for food, particularly in the southern regions which have a
large body of recipes and folklore relating to it.
The opossum is usually solitary and
does not have a territory, but is
always on the move, going wherever it can find food. It will eat any
available carrion but otherwise seeks out insects, frogs, birds,
snakes, and earthworms. It will catch and eat rats and mice if it can
find any, and is one of the few animals that regularly preys upon
shrews and moles. Its broad diet allows it to take advantage of many
sources of food provided by humans such as garbage and pet food, and
will raid their fruit trees as well. It doesn't hibernate in the winter
but will hole up during very cold weather until conditions improve and
it is not uncommon to see one wandering about on mild days. Many are
killed on the highway when scavenging road-kill so be on the lookout
for this ancient animal and give it the respect it has earned as an
interesting relic of the past.
February 10, 2009: Elephant Seals
I usually limit my writing to local
wildlife subjects, but our recent
experience along the west coast inspired me to share what we saw. We
visited one of the most interesting and unique of California’s state
parks, the Año Nuevo State Reserve, home of the largest rookery
for northern elephant seals in the United States. A boardwalk extends
some distance along the beach there, and the huge seals by the thousand
cover the sand only a few feet from onlookers. There the bulls fight
for supremacy (although we did not see that) and the seemingly
oblivious females produce and nurse their pups.
Hundreds of thousands of these animals
once inhabited the Pacific
Ocean, but they were slaughtered wholesale for the oil that could be
rendered from their blubber. (One adult male contained enough blubber
to produce 25 gallons of oil). By 1892, only 50 to 100 individuals were
known to remain anywhere, but when these were given protected status by
both the Mexican and U. S. governments, elephant seal numbers rebounded
amazingly, and today there are approximately 170,000 animals and the
number increases by about 6% each year.
Part of what fascinates us about many
of the animals that live in the
sea is the knowledge that their ancestors were land dwellers that
returned to the water. The fossil record for marine mammals is very
poor and we know very little about their evolutionary origins, but it
is thought that there were at least seven types. Two of these are now
extinct, but five have continued to thrive in the oceans, including
whales, dolphins, seals and dugongs. As early as 1883, it was
recognized that all had rudimentary and vestigial features
characteristic of terrestrial mammals, but it was also observed that
they differed in significant ways.
Whales and dolphins are believed to be
related to a now extinct group
of animals whose closest relatives today are the group that includes
the cow, the camel and the hippopotamus. The origins of seals are
unclear but it is thought that the earless types, like the elephant
seals, had otter-like ancestors that returned to the sea about 25
million years ago, while the eared seals, such as sea lions and fur
seals, came from bear-like animals. Dugong origins (dugongs are
plant-eaters related to manatees) are very obscure but their closest
relatives today seem to be elephants. All share a thick layer of body
fat or blubber, limbs modified to form paddle-like flippers, and
internal body organs that can tolerate diving into very deep water.
The elephant seal takes its name from
the large proboscis of the adult
male that somewhat resembles an elephant's trunk and is used in
producing extraordinarily loud roaring noises during the mating season.
It is shielded from extreme cold by its blubber more than by fur, and
has a very large volume of blood that contains a great amount of oxygen
for use when diving. Elephant seals spend up to 80 percent of their
lives in the ocean, and can hold their breath for over 120 minutes as
they dive to a mile beneath the ocean's surface in search of their
favorite foods, which include rays, squid, octopuses, eels, and small
sharks. They spread their powerful rear flippers and swim like a fish
while using their front flippers to steer, and are also surprising
agile on land where they can move faster than the average human over
sand dunes. Earless seals do have ears but they are just a couple tiny
holes on top of the head, making them very streamlined.
The elephant seal breeding season
begins in December, when the first
males arrive on the beaches. From fourteen to sixteen feet long and
weighing up to 2 1/2 tons, these huge bulls establish their right to
breed with bloody fights. The females are smaller and average ten to
twelve feet in length and weigh only 1,200 to 2,000 pounds. They begin
to arrive in late December, and in a few days give birth to pups that
were conceived the previous year. The pup weights approximately 75
pounds at birth, but grows quickly on its mother's rich milk that is
55% fat, and may reach 250-350 pounds in less than a month. At
this point the female comes into season and mates again, although the
fertilized egg does not implant in the wall of her uterus for about
four months. The theory is that the female is so weak after nursing and
fasting that she needs time to recover, and also since her gestation
period is only seven months, this allows the young to be born after the
she returns to the breeding ground the following year. After mating,
the adult females return to the ocean leaving the pups behind to fend
for themselves, an abandonment that somehow seems to work out
satisfactorily for most of the young.
The sight of these wild creatures,
previously only glimpsed on
television specials, was thrilling to say the least, and their recovery
has proved again the marvelous ability of nature to rebound from
catastrophe and ill use. Our world has survived major disasters in the
past, giving hope that it will continue to do so for eons to come.
February 3, 2009: Deer Me!
After two weeks in sunny California,
the snowy Wisconsin landscape was
a wake-up call that winter is far from over. Frozen pipes in the barn
and icy footing were only two of the problems we faced, but the sight
of deer raiding the bird feeder and trimming the apple tree, both of
which are only steps from the house, indicated that conditions were far
more critical for the wildlife.
Those animals that stay active
throughout the winter have evolved ways
to make it through until spring, but persistent snow cover and frigid
temperatures stress them to the extreme and many do not survive. Birds
and mammals have feathers and fur that are good insulators, trapping
warm air close to their bodies. Squirrels will use their large, fluffy
tails as windbreaks to protect their backs and heads, foxes wrap their
furry tails around their faces to keep them warm while they sleep, and
birds fluff up their feathers.
It is vital for a mammal to maintain
its body at a constant
temperature. In the Arctic, mammals have very thick fur, which
insulates the body by trapping air, and they have a layer of stored fat
under the skin that gives additional insulation. It has also been
observed that the body shape and size of many cold climate mammals
differ quite a lot from similar species living in warmer areas.
Biologists agree on two general rules: in the more northern ranges of
an animal, the outer parts or extremities including legs, tail, and
ears, tend to be shorter than in the regions to the south, and animals
tend to be rounder and bulkier as you travel further north as
proportionally the surface area of the animal decreases which results
in less loss of body heat.
An animal that has unusual
capabilities to withstand the northern
winter is the moose. An adult is very comfortable in temperatures down
to -30º F and is more likely to be troubled by the heat than the
cold. When the temperature reaches the mid 20's Fahrenheit in the early
spring, a moose will need to take steps to keep cool and it is common
to see one seek relief by lying in water. A calf moose does not seem to
change its behavior to keep warm until the temperature drops below
-20ºF, at which time it might lie down in the snow to increase the
amount of insulation around its legs.
Whitetail deer are not so hardy but
most survive, having adapted over
thousands of years to withstand relatively harsh conditions. Glenn Del
Giudice, a Grand Rapids scientist, contends that a deer's survival is
dependent upon its ability to maintain a sufficient balance of incoming
energy through food and out-going energy needed to move and to maintain
body functions. The primary adaptation is its long, thick winter coat,
which includes 1-inch-long guard hairs over thick under-fur that traps
warm air around the body. Deer also put on reserves of fat and protein
to help them through the lean months when food is scarce.
Deer prefer to winter in dense conifer
stands, where thick groves of
pine, cedar, fir, and spruce block cold winds and whose cones are
reported to emit strong infrared radiation. Dr. Giudice contends that
compared to needles, cones are on average 15ºC warmer and emit
such strong infrared radiation that they “stand out like candles on
Christmas trees”. The question might be asked as to how much the sun
shines during the northern winter to create such radiation, and whether
any resulting heating effect could be noticeable, but perhaps there are
other factors at play. Snow depths under stands of conifers are
considerably less than elsewhere, at any rate, so that deer need to
expend less energy moving about. (It is interesting to read that the
radiation from cones on conifers also attracts certain seed-eating
insects that are equipped with special receptors on their abdomens).
When severe winter conditions persist,
a deer becomes progressively
weaker and malnourished until the animal exhausts its reserves of body
fat. Fawns of the previous summer are generally the first to succumb,
and the next most susceptible are bucks, which often cannot build up
large fat reserves in fall because they expend too much energy during
the rut. Predation by coyotes, dogs, wolves, and bobcats is also
directly related to winter severity, and weakened deer are more prone
to collisions with autos and trains. High losses of the following fawn
crop may occur after a severe winter as malnourished pregnant females
tend to produce weak or stillborn fawns; still, does usually enter the
winter in peak health and with pregnancy rates that can reach over 90
percent, even a much weakened deer herd can rebound within a few years.
With our burgeoning deer herd, many
are suggesting that a large deer
kill this winter and small fawn crop next spring would be a good thing,
but this reasonable stance is hard to accept when Bambi and his sisters
are standing outside the living room window looking in hungrily. We
don’t begrudge the sunflower seeds they glean and only wish we had left
more standing plant material in the garden for them such as the old
Brussels sprouts stalks that have been eaten down to nubs. We also
could have provided over-wintering sites for a whole range of
beneficial garden animals such as birds, wasps, spiders, ladybugs,
frogs and toads by neglecting to clean up our garden and planting more
shrubs and other cover. Additional protection could also be offered by
adding such things as a rock pile, loose piles of tree leaves, grass
clippings or straw that might provide shelter for a whole range of
creatures. At least, we seem to be entering a milder period this week
so perhaps the worst is over for this year.
------------------------------------------------------
January 27, 2009: Snow Surprises
Pristine snow makes a perfect backdrop
to allow us to see many objects on the trail that would have otherwise
gone unnoticed. On the hilltop, I noticed tan specks sprinkled across
the surface, many of them cross-shaped. Close inspection disclosed that
there were two different types of debris, the crosses and others with
butterfly-like shapes (thick center sections with delicate "wings" on
each side)--obviously seeds, and a nearby birch pendant proved to be
the source. Each winter storm evidently erodes the end of the cluster,
dropping seeds and hulls onto the snow. Finches, especially redpolls
and pine siskins are particularly fond of these and it’s not uncommon
to see the little birds hanging upside down on these natural hanging
feeders, eating avidly.
Paper birch trees aren't native to
southern Wisconsin, but we certainly have lots of them and their white,
curling bark and their habit of growing in picturesque clumps make them
stand out clearly among the other trees. One hundred and fifty years
ago, our hills were covered with prairie grasses and flowers, most of
the trees being held at bay by frequent fires that killed back any
growing sprouts. Then, when early settlers controlled the fires, the
trees grew up thickly in all the untilled areas, mostly on steep
hillsides. The paper birch has mostly survived as multiple clusters of
smaller stems because the first trunks often succumbed to the bronze
birch borer, but it is still valued for its beauty, as firewood, and as
wildlife food, if not its lumber.
The other birch common to our area is
the river or yellow birch, distinguished by its ragged-looking
cinnamon-colored bark. Despite its usual preference for wet soil, we
have several relatively large specimens halfway up one of our
hillsides. The bigtooth aspen, with its pale greenish bark, and the
less-common quaking aspen, are also relatively short-lived cousins and,
although many have died, some have matured and are being harvested as a
clear-grained lumber source. We have one bigtooth aspen whose trunk
must be twenty-four inches in diameter, but we know that its days are
numbered, as disease will surely strike it before long.
On sunny winter days, it is not
uncommon to come upon an insect making its way across the path. Usually
such creatures go unnoticed, but surprisingly, our northern winter is
the primary season of activity for some of these tiny residents.
Although most insects are cold-blooded and either die or become
inactive when their surroundings freeze, a few specialized species
regularly perform at cold temperatures, and how and why they do this is
one of the challenges biologists face. It is easy to theorize that
winter emergence has the advantage of little competition and reduced
numbers of natural enemies like birds, toads, and parasites, and it is
true that snow and ice are superb insulators for both plants and the
animals. But the critical factor seems to be that the bodies of these
insects, like those of some other winter and high-altitude creatures,
contain a natural antifreeze which allows them to function at low
temperatures.
Springtails are inconspicuous,
wingless insects and received that name because of the forked structure
clasped tightly to their undersides, which acts as a catapult to flip
them into the air when danger threatens. They feed on rotting plant
material and pollen and usually remain buried in leaf litter until snow
inexplicably brings them to the surface. On bright days their bodies
absorb enough heat from the sun to keep them active, although at night
they lie frozen. They measure barely 1/16th of an inch and sometimes
resemble specks of soot, yet what they lack in size, they make up for
in numbers, with populations of up to tens of thousands per square
yard. Hordes of these tiny primitive insects may blacken sunken
patches of snow, such as footprints and tire tracks, or assemble at the
base of a tree on a sunny day.
Another winter insect, the snow fly,
is a crane fly whose summer relatives resemble giant mosquitoes. Not
the winter species, however, which lacks wings and has long fuzzy legs,
and looks like a spider. Most of the winter it remains in leaf litter
or under logs and stones, but on mild, sunny days, it will emerge in
search of a mate. After mating the female will burrow down close to a
tree trunk and deposit her eggs.
Most surprising of all are the
caterpillars that we sometimes see on top of the snow. Curiosity led me
to call the university extension, and I was told these were probably
the larvae of a geometric moth, an unobtrusive common insect that
winters among the leaves and grass and perhaps mistakenly took the
warmth of the sun on its dark body for the end of winter. They, like
us, can't wait for spring!
---------------------------------------------------------
January 20, 2009: Foxy Things
There was a faint skunk smell along
the trail that I probably would have missed had not Daisy's sensitive
nose led us to the source, a pile of scat deposited on a clump of
frozen dirt and stained with urine. The droppings were plainly those of
a fox and I guessed that a pair had come by, reserving our trail as
part of their territory. In January, each reynard and vixen (the
traditional names for a male and female fox) reestablish their bond and
hunt together for several months, scent marking as they range. The
"foxy" skunk smell comes from a small scent gland located beneath the
tail, and the output mixed with urine serves to warn other foxes of
their presence.
"Vixen" and 'foxy" were two common
English words with colloquial meanings in years past because everyone
was familiar with the wily animal. Neither word is often used these
days, but it is not because foxes are gone, only that they are so
secretive that few people know much about them. In Wisconsin, there are
two species, the red and gray, and almost every rural area harbors one
pair or another.
Foxes are most active at night, and
their home range may cover several square miles. Their large sensitive
ears can detect a mouse 150 yards away and they also hunt voles,
squirrels, rabbits, birds, and fish, and will eat wild fruits, grain,
and even carrion. The den is usually an underground burrow that may be
up to 30 feet long with multiple entrances, or a deep crevice in a
rocky outcrop. The red fox's night-hunting and day-hiding habits seldom
allow us to glimpse it, but it leaves tracks on the snow each winter.
The individual print is roundish and about 2" across, in contrast to a
house cat's 1 1/4" or the coyote's 2 1/2" width, and often shows a
unique inverted V-shape ridge across the center of the heel pad. An
animal sometimes doubles back on its own tracks in order to confuse an
enemy and can run up to 30 miles per hour and jump over a 6' feet high
barrier to avoid capture.
The red fox is a small animal, at
least compared with a coyote or our collie, and weighs only about 15
pounds. It typically has a rusty-red coat with white underparts and a
long bushy tail tipped with white. There is also a "silver" phase that
is almost completely black with silver tipped hairs, and sometimes a
"cross" phase that is a mixture of the two. According to a University
of Wisconsin arboretum publication, the red fox may not be a native
species, as it was not found in the eastern and southern areas of the
country when European immigrants arrived. In the early 1700s, however,
sport hunters among the settlers began importing and releasing European
red foxes, a slightly different species from the more westerly American
red fox, in that it was a darker red and larger-bodied. Much forested
land was being cleared by logging and fire, and these adaptable aliens
moved into the newly created habitat. It is believed that the Wisconsin
population of red foxes is primarily made up of descendents of these
non-natives.
The gray fox is sometimes mistaken for
the red fox, but is somewhat smaller and frequents slightly different
habitats. Its coat is grizzled and often has quite a bit of red, but
the tip of its tail is always black. Gray foxes are found in
deciduous woodlands and are occasionally seen in old fields foraging
for fruits and insects, but unlike the red fox they are not commonly
found around active farms. Gray foxes are nocturnal and den during the
day in hollow trees, stumps or old woodchuck burrows.
The gray fox is notable for its
ability to climb trees and jump from branch to branch, a skill that
allows the animal to safely feed, den, and escape earth-bound
predators. It frequently runs up sloping tree trunks, but can climb
vertical ones as well by wrapping its forelimbs around the trunk while
pushing with its hind feet, or by using its strong, hooked claws, much
like a cat. The most important food source for the gray fox is probably
the eastern cottontail but it also feeds upon voles, field mice,
shrews, and birds, supplemented with whatever fruits are readily
available. Gray foxes breed 2-4 weeks later than the red foxes and
rarely dig their own dens, preferring to use hollows in standing trees,
logs, buildings, or rock crevices
Few foxes live beyond the age of 3 or
4 years, particularly in areas where they are hunted and trapped
heavily. I understand that half a million gray foxes are trapped
annually to meet the ever growing demand for fur, and in Wisconsin
alone, half the gray fox population is killed off every year. They are
also susceptible to a variety of diseases, including rabies, distemper,
and infectious canine hepatitis. We once came upon the carcass of a
half-grown youngster without a mark on it and guessed it was victim of
some fatal infection. Nevertheless, even with disease and heavy
harvests, our fox numbers do not seem to decline and it is likely that
we will continue to enjoy the presence of these beautiful and clever
animals for many years to come.
--------------------------------------------------------------------------
January 13, 2009: Giving a Hoot
Just when we think winter is settling
in and nothing much could be
going on out in all that cold and snow, we hear a great horned owl
calling to his mate and realize they are already busy setting up
housekeeping for the new nesting season. They have been whoo-ing and
hooting for a month or more now and if we could spy on their meetings
we would probably see them taking part in the time-honored courting
ritual. The pair will bow to each other, holding their wings down at
their sides, rub bills and preen each other’s feathers. Wouldn’t it be
fascinating to know of just how much affection these big aggressive
birds are capable?
Great horned owls are the earliest of
spring nesters,
and it is not
uncommon to find a brooding female almost completely covered with snow.
A pair does not build a new nest of their own but either renovates last
year’s or else takes over one of another large bird, a squirrel nest, a
tree hollow, or a nitch in an abandoned building. One does well to
avoid such areas, incidentally, as the owls are fierce in their defense
of their nests and are notorious for attacking anybody or anything that
dares to venture too close. I remember hearing the story of a
passerby who received holes in his hat and punctures in his scalp from
an attack by a nesting owl.
Normally, the female will lay and
incubate two to four eggs for about
four weeks, and it requires another 2 ½ months after hatching
before the young owlets begin to fly. It is then a challenging process
for the parents to teach them to hunt, and it is often autumn before
the young birds are able to move off and take care of themselves.
Although adults tend to remain near their breeding areas, juveniles
disperse widely—some banded birds showing up 150 miles away.
Territories may be maintained by the same pair for many years, but
these owls are solitary in nature, only staying with a mate during the
nesting season. Average home ranges have been shown to be approximately
a square mile.
Often more than two feet in length and
with a wingspan that may stretch
up to five feet, the great horned owl can easily carry off a rabbit or
skunk (it is the only animal that regularly eats skunks), and will kill
other owls and hawks if it gets the opportunity. It hunts by perching
on a snag or branch, diving down to the ground to snatch up any unwary
animal that appears. Rodents and very small rabbits can be swallowed
whole while larger animals are carried off and ripped apart at feeding
perches or at the nest. An extremely wide range of creatures are taken,
including mammals, birds, reptiles, amphibians and insects, and the
owls are not above dining on road kill or other carrion. Owls extract
the nourishment from their prey and then compress the inedible parts
into gray oval pellets and later disgorge them. The objects are very
large, about 3- 4" long and 1.5" thick, and often include skulls and
other bones, as well as fur and feathers, and are regurgitated about
eight hours after eating.
All owls are uniquely adapted to their
mostly nocturnal life,
possessing large skulls that are almost entirely filled with enormous
eyes and ears. The eyes of great horned owls are nearly as large as
those of humans and are fixed within their circular bone sockets so
that instead of moving them, they have to turn their heads. Their necks
can turn a full 270 degrees, as they have extra vertebra in their
necks, but they are not able to swivel all the way around as some myths
would have it.
Nighttime hunters have large
protruding corneas to let in any available
light, and lenses whose shape can often be altered by specialized
muscles to allow for focusing under difficult conditions. Their retinas
are provided with thousands of rod receptors that will receive very
reduced amounts of light energy, as well as additional layers of cells
behind them. This tissue layer serves as a reflector to improve the
efficiency of light gathering in the eyes by bouncing it directly back,
giving the retinal cells two chances to absorb each photon. This latter
characteristic is called “eyeshine” and makes some eyes seem to glow in
the dark when illuminated by a car’s headlights. It is said that an owl
can see as well on a dark, starless night as a human does on a cloudy
day.
An owl also has particularly large ear
openings that are equipped with
moveable skin flaps that funnel the sound waves into them. Also, one
ear is located higher on the head than the other so that by tilting or
turning its head until the sound is the same in each ear, an owl can
pinpoint both the horizontal and vertical direction of a sound with
great accuracy.
The best clue to the daytime presence
of an owl in your neighborhood is
a noisy flock of crows, as these birds will congregate from long
distances to mob one, and may continue the hubbub for hours. The great
horned owl is a regular victim of this harassment but the crows’ enmity
is well earned, as this owl is probably the most important predator on
them and their nestlings. After dark, the crows are silent, but the
owl’s calls will echo back and forth between the hills. Step out the
next clear night and listen to see if a great horned or any other owl
is nearby.
---------------------------------------------------------------
January 6, 2008: A Hawk Hazzard
The once beautiful Cooper’s hawk lay
stiff and bedraggled on the
plastic bag, victim of an all-to-common collision. The bird had
evidently been in pursuit of one of the visitors at a feeder in town
and flew right into a window. It was about 17 inches long and probably
a female, as males are usually smaller, and it had a sharply hooked
bill and long sharp talons. A Cooper’s hawk captures prey with its
feet, and will squeeze it repeatedly to kill it, instead of using its
beak to kill as would a falcon.
We have three very similarly marked
“bird” hawks—the Cooper’s, the
sharp-shinned, and the northern harrier (once called the marsh hawk).
The sharp-shinned is the smallest, and may measure as little as 10
inches from the tip of the beak to the end of the tail, the Cooper’s is
middle-sized at 14-20 inches, and the harrier is the largest and may
reach 24 inches, although I read that their sizes are so variable that
it is often difficult to distinguish between them. The harrier does
have a white patch on its rump that sets it apart if that is visible.
All three hawks prey upon smaller birds and have short, rounded wings
and long tails that allow them to maneuver deftly between trees and
around obstacles in pursuit of their prey. Dashing through vegetation
to catch birds is evidently a dangerous lifestyle, however, as a recent
study found that 23 percent of all examined Cooper's had healed
fractures in the bones of the chest.
The Cooper’s usually lives in the
woods, but has learned that in the
winter, feeders are a handy location at which to capture a meal.
Declines of their numbers in the late 1940s and 1950s were blamed on
DDT and other pesticides, but more recently, their population has been
increasing, perhaps because of the move into more urban and suburban
areas. Far more Cooper’s were seen during the last December bird count
in Wisconsin than any other hawks, with the exception of the red-tailed.
“No one knows what birds see when they
look out at the world,” says
ornithologist Daniel Klem, a professor at Mulhenberg college in
Allentown, Pa., “but they sure don't see glass.” He estimates
that a billion birds are killed by hitting windows each year, or
roughly five percent of those present in the United States each fall.
Although cell phone towers, oil spills and power lines raise the ire of
conservation groups, those hazards pale in comparison to glass, Klem
pointed out, and states that only habitat destruction is more
detrimental to the birds.
That figure may seem high, but the
fact is that great numbers of the
feathered creatures die from collisions with our homes and businesses,
and the problem is finally getting attention. Birds fly into glass for
several reasons. Daytime strikes occur because birds cannot understand
that images visible on the glass are reflections, and crash into
windows that they assume are trees or sky. Then, too, light pollution
from urban areas obscures the brightness from the moon and stars at
night and disorients and draws them into brightly lit downtown areas
where they may strike buildings or windows.
The city of Toronto, Canada has
published bird-friendly development
guidelines that recommend design-based strategies, such as using
non-reflective glass, placing visual markers in lower windows,
redesigning ventilation grates and placing large indoor plants away
from windows. In city owned buildings, a lights-out policy for after
work hours and on weekends has been in force since 2005. The city
government is also participating in the rescue, rehabilitation and
release of injured birds.
The developers of New York's
1,776-foot Freedom Tower, which is being
built on the site of the World Trade Center will incorporate innovative
designs to reduce bird deaths. They plan to use as little reflective
glass as possible at lower levels, position trees and vegetation to
minimize their reflections in the glass, and avoid planting trees in
atriums with a clear facade.
Swarthmore College recently agreed to
turn its new science center, that
features a three-story meeting room faced with clear glass, into an
experiment to find solutions to the window hit problem, by using it to
test a new kind of glass designed to ward off oncoming birds. This
hopefully bird-friendly "fritted" glass is etched with closely spaced
rows of small circles that make the glass hard to see through when
standing right in front of it, but from a slight distance, the markings
almost seem to disappear.
It is not only urban buildings that
cause bird fatalities, as most of
us with picture windows have seen such accidents in our own yards. A
suggestion that may mitigate the danger around your home is to place
bird feeders either within three feet or else at least 33 feet away
from your windows. Many people also try to alter a problem
window's appearance with decals, screens, branches or window film with
varying success. It may help to draw drapes or close blinds, and some
have gone so far as to install stained or frosted glass. Birds and
windows are never going to be completely compatible whatever we do,
however, but with so many of their populations decreasing, we must do
whatever we can try to minimize this type of accident.
------------------------------------------------------------------------------
December 30, 2008: Stars on our
Shoulders and Under our Feet
I suppose most of us have mixed
feelings about snow. Looking out the
window at the full moon shining on a pristine field marked only by the
tracks of foraging deer, or bundling up and walking through a quiet
white world as flakes come floating down are the scenes of which
Christmas cards are made, but snow also gets in our way, makes travel
difficult, and it often becomes ice, threatening life and limb.
The smaller mammals are probably
grateful for snow, and the deeper the
better. Lots of life exists under its surface -- mice, voles, shrews --
and the predators that search for them, like weasels. Typically,
temperatures are above freezing in winter lairs under the snow, and may
be up to 50 degrees warmer than the night air outside. The animals
create multiple burrows under the snow, leading to stored-up food
supplies so that they seldom, if ever, have to venture up into the
dangerous world above. Snow offers some safety—but tunnels near the
surface are vulnerable, because owls and coyotes often hunt by sound,
and an ill-timed squeak or rustle can bring their claws punching down
through the crust.
Rodents are not the only beneficiaries
of a white winter, as snow is a
superb insulator that prevents our below-zero temperatures from
damaging vulnerable plants and all the insects and other creepy
crawlies that are over-wintering. And when the weather really becomes
bitter, ruffed grouse have been known to either burrow below the
surface or fly directly into a soft snow bank, where temperatures are
more tolerable.
When we first venture out after a
snowfall, we can see that the surface
is comprised of untold numbers of individual flakes. What isn't readily
evident is that each flake is made up of clumps of many separate snow
crystals. Snow clouds are composed of microscopic water droplets and
particles of dust and salt that the wind has lifted high into the
atmosphere. The droplets are attracted to these bits of matter and then
freeze, sometimes developing into very complicated crystals.
In general there are four different
shapes of snow crystals. The
simplest are long needle-shaped spikes while others are hollow columns
or thin, flat plates. Most beautiful and what we usually think of when
we visualize snowflakes are the intricate, six-pointed stars. The shape
that a snow crystal takes is dependent upon the conditions at which it
was formed.
The temperature in the highest clouds
is around -30°F and moisture
is in the form of ice crystal columns. The other three shapes are
formed lower in the clouds where it may be as warm as 32°F. Highly
branched crystals tend to have more space between the arms of ice that
form the snow flake and this snow will therefore have a lower density,
often referred to as "dry" snow. Conditions that create columnar or
plate-like crystals will have much less air space within the crystal
and will therefore be denser and feel "wetter".
As the snow crystals grow they become
heavier and fall towards
Earth. If they spin like tops as they fall then they may be
perfectly symmetrical when they hit the Earth but if they fall in a
sideways fashion then they end up lopsided. No matter what their shape,
in a very short time they lose their individuality and their
crystalline structure and change into small granules of ice. At this
point they become “snow”. Once the snow is on the ground, it will
settle under its own weight and begin to evaporate until its density is
approximately 30% of water. Melting and refreezing caused by warmer
temperatures and direct solar radiation can bring the snow density up
to 50% of water by late spring.
In 1611 Johannes Kepler published the
first scientific reference to
snow crystals. Kepler raised the question of why snow crystals always
exhibit a six-fold symmetry but it would be 300 years before his
question could finally be answered. In 1665 Robert Hooke published a
large volume containing sketches of many snow crystal drawings he could
view with the newly invented microscope, which for the first time
revealed the intricate symmetry of snow crystal structure. In 1931,
Wilson Bentley, an American farmer, photographed some 5000 snow crystal
images through a microscope and published his famous book, Snow
Crystals.
In 1954, Ukichiro Nakaya of
Japan was the first to grow
artificial snow crystals in the laboratory under controlled conditions
which provided extremely important information for understanding the
physics of snow crystal formation. He made a series of very detailed
observations of all types of frozen precipitation, identifying and
cataloging all the major snow crystal types. Unlike Bentley,
Nakaya photographed the great variety of snow crystal types, not just
those that were the most beautiful and symmetric.
In case you are feeling that the
snowfall these past two years has been
excessive, consider these facts: the highest seasonal total snowfall
measured in the United States was at Mount Baker Ski Area outside of
Bellington, Washington during the 1998–1999 season, where they received
1,140 inches of snow, and Guinness World Records list the world’s
largest snowflakes as those of January 1887 at Fort Keogh, Montana
where one reportedly measured 15 inches wide and almost 8 inches thick.
Imagine that falling on your head!
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December 23, 2008 Look to
the Stars
While the sun is a welcome sight these
cold winter days, it is the
nighttime skies that are spectacular. A short time ago, the full moon
shining on the snow was seemingly bright enough to turn the night into
day, but the heavens are more interesting now that it has waned and the
sky is darker. Looking to the west and then up across the sky
almost overhead you should easily be able to pick out the path of the
Milky Way. It appears as an indistinct band of light, but if you have
binoculars and focus on any part of the area you may be surprised to
realize that what you are seeing are untold numbers of tiny stars too
far away and dim to be distinguished with the naked eye. Located as we
are about two-thirds of the way out to the edge of the galaxy and
looking across and through its flat spiral of stars and gaseous clouds,
we can look towards its center in the summer months and see the Great
Sagittarius Star Cloud, the beautiful star-filled hub. At this time of
year, the sun obscures this part of the sky, but other equally
fascinating stars have come into view.
The sky that we see is virtually the
same one that was visible to the
earliest humans, but we, with our more advanced knowledge of the
universe and what stretches beyond it, can rove in our mind’s eye to
distances beyond comprehension. Fascination with the stars was
just as intense in earlier centuries, however, and the people of those
times saw beings and objects and creatures outlined in the lights and
devised tales to go with them. Bears, a swan, a lion, a hunter,
an eagle, a great serpent, even a beehive -- all are blazoned across
the heavens for those with imagination who know where to look.
Some are difficult to pick out and may
seem rather indistinct to our
photograph-accustomed eyes, but each has its story and place in the
sky. The most recognizable winter group is found by looking for the
line of three bright stars half way up in the southern sky. These three
and the several dozen stars of varying brightness surrounding them make
up the constellation Orion. Because it is situated above the earth’s
equator, this configuration is visible from every corner of the earth
and features in the myths of all the various cultures.
In our tradition, Orion was a Greek
hunter and is often pictured with
raised club and shield, with a sword on his belt, and facing Taurus,
the bull. The constellation contains a number of very bright
stars. Betelgeuse, with its yellowish red color, is part of his
shoulder, while Rigel, an even brighter white star is in Orion’s leg.
The great Orion nebula, a cloud of gases and very hot young stars, is
located in his sword and is one of the few of these phenomena visible
with the naked eye. Other major constellations prominent in December
are Cassiopeia which was named for a mythological queen and is made up
of five stars in the form of an “M” in the winter and a “W” during the
summer months, and the Great and Little Bears, which are formed in part
by the Big Dipper and Polaris, the north star.
Probably, the most often pictured star
is the one mentioned in
Christian scriptures that led the Magi to Bethlehem. These “Wise Men”
are thought to have been astrologers, men who studied the heavens
looking for anomalies that might be portents of earthly occurrences
such as famine, war or peace, or in this case, the fulfillment of a
prophesy. At this time, most astronomical observation was done by those
with astrological motives, but they plotted the location and motion of
celestial objects with considerable accuracy and were well equipped to
notice unusual phenomena. Some modern scholars have suggested that the
star of Bethlehem could have been a spectacular natural happening, and
astronomers through the centuries have reported several such events
that did occur very close to the time of Jesus’ birth. In 1614, German
astronomer Johannes Kepler determined that a series of three
conjunctions of the planets Jupiter and Saturn occurred in the year 7
BC, an important astronomical event and one that probably would have
been deemed a miraculous sign to people of that time. Others have
suggested it might have been a comet or even a super-nova but neither
of these appear in old records.
Whatever the origin of the story, the
awe with which we gaze at the
heavens is never more intense than at this holy season of the year, and
I hope you will take a break from your holiday bustle and step outside
and see the stars.
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December 9, 2008 Snow
Stories
Much of the time we are oblivious to
the visits of local wildlife in
our yards or on the trails, as most of the animals remain in hiding
during daylight hours and only venture out as darkness descends. This
changes abruptly when snow falls and the ground is covered with a
pristine sheet that records the passing of even the smallest creature.
The area under our feeders becomes a mishmash of imprints and by the
second day, the tracks are not only those made by birds but by a
variety of rodents as they joined in the feast.
The tracks of all rodents, including
mice, voles, chipmunks, squirrels,
woodchucks, muskrats, and porcupine, show four toes on the front foot
and five toes on the hind foot. If you find a track like this, size is
the first consideration in identifying its maker, as the latter three
animals will have a considerably larger track than the first ones. We
can eliminate the porcupine, as one is highly unlikely to be seen in
our area, and up in our hills muskrats are also very scarce. Chipmunks
and woodchucks are asleep snug underground, so that leaves the only
possible perpetrators to be rats, mice, voles, and squirrels.
Squirrels leave interesting tracks as
they bound along, their larger
hind feet landing ahead of their smaller front feet, and they usually
hop from tree to tree and dig holes. Mice and voles also hop at times,
but are much smaller. Conditions have to be very good to see the tiny
toes on their tracks, and these trails are often confused with those of
the shrew that has five toes on both the front and back feet.
Typically, mice leave a four-footed pattern, something like a tiny
squirrel, while voles have paired tracks and often tunnel down into the
snow if it is deep enough. The individual track of a Norway rat is
twice the size of those of the other three.
Four toes on each of the front and
hind feet means you're looking at a
track from the family dog (or fox, coyote, or even a wolf), or a cat
(or bobcat). A cat seldom leaves the small triangular claw marks in
front of its paw print, because it retracts its claws when it walks or
runs, while the tracks of the dog family usually do. Dogs tend to
meander, while coyotes and foxes usually travel in a straight,
purposeful, line.
If the track has five toes each on the
front and back feet it is from a
raccoon, bear, opossum or a member of the weasel family, such as a
weasel, badger, mink, skunk, or otter. Weasels leave unique tracks in
the snow. The trail usually appears as a pair of twin prints, often
with a long leap, then a shorter one, sometimes changing direction
suddenly, even looping back upon itself, and can disappear under a log
or into a snow bank. The tracks are also distinctive as each shows a
heel as well as five toes, characteristic of only the weasel family.
Raccoons are much more common and have noticeably large rear feet,
while opossums have a protruding "thumb".
Rabbit tracks look a little different.
As the animal hops, its hind
feet also land ahead of the front feet, but it often places one fore
foot in front of the other forming a triangular pattern, in contrast to
the squirrel whose front feet leave tracks that are side by side. And
deer are unmistakable with their two-toed track.
Size of track, the width of the trail,
and the distance between groups
of prints are all good clues to the identity of the animal, but these
vary so much with snow conditions and the speed the animal is
traveling, that they are only hints. If it had claws they will point in
the direction the animal was going, and if there aren't any claw marks,
you may be able to see where the snow is pushed back by the animal's
feet showing the direction from which it came. Reading tracks is not
often easy because details may not show plainly. For example, the track
is often incomplete and will look different after the wa