Thursday, October 29, 2009

Tamaracks

Nature Watch
By Susan Benson,
CNHM Director of Education

Autumn Gold

The autumn gold colors of the tamaracks that greeted us this past week have been a joy to see. Although the tamarack tree resembles other evergreens, it is actually a deciduous conifer, so it sheds its needles every fall. It grows in cold, wet, poorly drained sites such as swamps, sphagnum bogs, and occasionally in upland soils. The pale green needles are soft, about one inch long, and grow in brush-like tufts along the twig. In the fall, just before the needles drop, they turn a beautiful golden color, providing a striking contrast to the last of the fall foliage.

Tamaracks have some other interesting characteristics. Their life expectancy is up to 180 years. They are cold tolerant and able to survive temperatures down to at least -85 Fahrenheit. The tree casts a light shade, so tends to have a dense undergrowth of shrubs with speckled alder, willows, red-osier dogwood, Labrador-tea, bog-rosemary, leatherleaf, or blueberries growing beneath. Because of its intolerance to shade, tamarack stands are usually even-aged.

The life cycle of a tamarack is appealing. In a bog, a tamarack tree is usually the pioneer, the first tree to establish itself in the sphagnum moss mat floating over the water.
It leafs off in the early spring before the ground has thawed, and takes four to six weeks for the needles to develop. In open areas, tamaracks can begin seed production when they are fifteen years old, but most pine cone crops come from trees that are 50 to 150 year old trees. One tree can produce as many as 20,000 cones in a good year, which can happen every three to six years. They can also produce root sprouts up to thirty feet from the parent tree. In mid-October the needles begin to change color. By the end of October, most of the seeds have dispersed, primarily through wind, but also by red squirrels forgotten caches. Most wind-dispersed seeds fall within two tree heights of the parent tree.

Animals interact closely with the tamarack tree. It is estimated that due to the consumption of seed off the ground, half of the crop is destroyed. Red squirrels cut and cache the cones for later eating. Mice, voles and shrews consume large numbers of seeds off the ground. Pine siskins and crossbills eat the seeds. By the time bacteria and fungi have “fed” off the seeds, it is thought that only about four to five percent of the seed that reaches the ground actually germinates. Additionally, snowshoe hares feed on twigs and bark, porcupines on inner bark. Ospreys sometimes choose to rest in dead tamarack, as do bald eagles on occasion.

Tamarack trees have an interesting natural and human history. Following the last ice age, it was one of the earliest species, along with spruce, to follow the retreating ice northward. Native Americans used the roots for cordage, the wood for arrow shafts, and the bark for medicine. Roots were used for sewing canoe edges. Early Americans used soft needles for stuffing pillows and mattresses. The wood was used widely for ship building, for timbers, planking, and to join the ribs to the deck timbers. The inner bark was used to treat melancholy, and the bark contains tannin that has been used for tanning leather.

Tamaracks seem to be sitting on the fence when it comes to deciding whether to be categorized as a conifer or a deciduous hardwood, and certainly cannot be called an “evergreen.” Regardless, we continue to benefit from their autumn beauty.

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, October 22, 2009

Dark-Eyed Juncos

Nature Watch
By Susan Benson,
CNHM Director of Education

Driving along the road this past week, I was greeted by the white flash of tail feathers from a quickly departing flock of birds from the roadway. Many of us have probably observed that each flock flies away from the road, and often lands back on the road behind us as we travel along. This spark of color belongs to the dark-eyed junco, one of the most common birds found in North America. For northern Wisconsin, a junco is a year-round resident, but juncos still migrate from Canada to disperse throughout much of North America during the winter. As they migrate, they are often observed scavenging seeds along the roadsides. The flash of color we see as they fly occurs as they pump their tail to show their white outer tail feathers. Their coloring mimics a winter scene with its dark gray above and snow white below. We can also enjoy these birds in other places as well, on woodland walks or at our bird feeders.

Juncos are primarily seed-eaters, feeding on many plants we might be familiar with – lamb’s quarters, chickweed, and sorrel, which make up three-quarters of their diet. They are one of the few bird species that usually prefer millet and cracked corn over sunflower seeds. In the spring, they often add insects such as caterpillars, beetles, moths, ants, and flies to their diet.

When foraging, dark-eyed juncos are seen hopping along the ground, scratching like a chicken at the leaf litter, or sometimes maneuvering successfully through low, tangled undergrowth to find food. During the summer males are very territorial, but in winter, they form large flocks of ten to thirty birds that can also include several other sparrows. Junco flocks have a “pecking order,” as early migrants have a higher status than later arrivals.

If you see a bird flock and are interested in identifying the dark-eyed junco or other species, grab a bird field guide and try to identify white-throated, white-crowned, chipping, or American tree sparrows. Also, don’t be surprised if what you first think is a junco or other sparrow is actually a yellow-rumped warbler, as they are one of the other last migrants to leave our area. Migrate yourself outdoors to discover what birds you can find!

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, October 15, 2009

Goose Music

Nature Watch
By Susan Benson,
CNHM Director of Education

Goose Music

Almost daily it occurred this past week – the honk of a flight of geese in their migration flight, their voices in constant contact—what Aldo Leopold called “goose music.” Most flocks can number thirty to one hundred birds as they travel up to forty miles per hour at an altitude of 2,000 up to 30,000 feet. It is a sight everyone is used to seeing across the country and is a sound almost everyone knows. Canada geese are amazing birds that have been studied by scientists for many years.

Historically, it was a shock to many scientists to discover that many species migrated. Some naturalists felt it was impossible for tiny birds to fly so far without help. They conceived the idea that larger species, such as cranes, storks and geese, would carry these smaller birds as “living freight.” Some Native American tribes in the Western Hemisphere held beliefs that hummingbirds would ride on the backs of geese. Today, scientific study has taught us much about Canada geese and their success in migration.

Preparation for migration begins from the moment Canada geese hatch. Adult males begin molting right after mating, and the females begin five weeks after the goslings hatch. The adults re-grow their flight feathers and are ready to fly at about the same time as the goslings are able to learn - at nine weeks old. The parents teach them to fly, usually running along the surface of the water or ground for takeoff. As soon as the young are strong enough for the trip, the family begins their migration south. The young learn the migration routes from their parents and follow the same route in future years. Then the familiar v-shaped formation flight pattern begins.

Why do geese fly in a v-formation? Because it is hard to fly in an s-shape. Just kidding. In reality, the v-shape requires less energy, allowing the geese to fly longer distances. By flying slightly above the bird in front of them, there is a reduction in wind resistance. Geese can use fifty to seventy percent less energy due to the lead bird’s updraft. They can also travel at least seventy percent further than when flying alone. The larger, stronger birds are usually the leader. The lead birds rotate in a timely fashion to keep fatigue from occurring among the flight members. While flying in the v-formation, they can also communicate easier, and keep visual contact with each other.

Why are geese so loud when honking while in flight? It is believed that they are “cheerleading,” encouraging the leaders to keep up the good leadership, and to keep going! When they do travel, Canada geese stay in family groups. When ready to feed and rest, they land in familiar marshes or fields. When a large flock of geese comes in for a landing, family units “peel” off in smaller groups before they land. The next morning the arduous flight to central or southern United States continues.

It is amazing that geese, or any birds, continue to make the migration south with all the challenges they can face. When cloudy, birds may fly closer to the ground. They can have troubles with exhaustion from long flight with not enough rest. Bad weather such as snowstorms, thick fog, or strong winds can impact their success. Starvation from not enough food can occur. They can also fly into human obstructions or be shot by hunters. As we wish for their success in the coming days, we can continue to enjoy their goose music and flight overhead, soon to be a sound that will disappear until spring.


For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, October 8, 2009

Bird Migration

By Susan Benson,
CNHM Director of Education

It is estimated that as many as five billion birds migrate through the Americas every year. Approximately two-thirds of all North American bird species migrate. This means they travel from a breeding area to a wintering area and back again. They eat more food to gain fat for the flight. They molt old feathers, growing new ones. Many of these birds travel thousands of miles. They have no GPS or maps to navigate through the sky. The migration is timed so that young hatch as spring and fall berries and seeds ripen and insects arrive or decline. Finally, think of the ruby-throated hummingbird alone, whose weight is that of a penny, is about three inches in length, and makes a flight trek of thousands of miles while keeping a course through winds and weather. Bird migration is truly one of nature’s annual wonders.

Most scientists believe that birds navigate using the sun or stars as a compass. Some believe there is a chemical, a molecule called a superoxide, in birds’ eyes that allows them to sense the Earth’s magnetic lines as if there were a highway through the sky. Others believe the iron-rich magnetite crystals found in many birds’ brains allow them to detect the magnetic fields. Using visual landmarks, making mental maps, using olfactory cues, or genetic or environmental influences may also be amazing factors that help birds succeed with navigation and orientation.

Migrating birds generally move from north to south and from south to north. However, there are several birds that migrate over regular routes diagonally or even east to west before arrive at their destination. These diagonal travelers usually move only to the lower edge of their summer range in winter, travel east-west to a sea coast, or simply move to a lower altitude in the same place.

In late summer, before migration, the metabolism of migratory birds undergoes extreme changes. The actions of the hormones prolactin and corticosterone cause migratory birds to accumulate large amounts of fat under the skin. These accumulations provide energy for long flights.

Some birds migrate during the night to avoid predators and to eat and rest during the day. Nocturnal migrants will utter sharp and melodious peeping and piping calls, allowing individuals to stay in touch with each other.

Each bird creates behind it a small area of disturbed air during flight. Birds have learned to use this air to their advantage during migration. Air lost over the wing tips creates a spiral vortex behind each wing tip, with upswelling air on the outer side of each wing. Birds that migrate together fly aside or slightly above the bird in front and use less energy.

Migration is a very strenuous activity that requires extreme amounts of energy. Some birds will fly four to six days straight without any rest. Some researchers estimate that an equivalent feat would be similar for a human to run four-minute miles for a total of eighty hours!

We may never discover the scientific mysteries of the phenomenon of this annual cycle. Keeping a bird journal can help us learn a little more about our feathered friends. Record observations on a calendar and jot down some notes. Include any other observations of these birds. Perhaps you will discover a clue to solve the mystery of migration.

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470

Thursday, October 1, 2009

White Footed Mouse

Nature Watch
By Susan Benson,
CNHM Director of Education

Last night I had a guest over for dinner. She spent several hours, not creating much quality conversation. She dined mostly on chocolate, one of my favorite foods. Normally, though, she loves cherries, as she always leaves large piles of seeds behind when she goes. She was not one to sit for long periods, preferring constant movement, just like a young child squirming in her chair. I know this guest well, as she has been a regular visitor to my home for many years. I am always struck by her lovely brown hair with her big, brown eyes. As we sat watching a movie after dinner, I smiled at the behaviors of my regular visitor, the white-footed mouse. As she scurried back and forth in my living room, she was perhaps a bit rude to not spend more time sharing with me what her actions were. I woke up this morning, still pondering what she was doing while visiting the house, with plans, I’m sure, of becoming a permanent resident.

White-footed mice can be recognized by their rich, reddish brown fur, with a white belly and feet, and a tail almost half its entire body length. These mice are primarily nocturnal, solitary and are territorial, though their home ranges do overlap. White-footed mice climb and swim well. I can agree with this, as last night’s visitor was on the second story of my home, and I have been surprised in the past by watching these daring travelers climb walls in what seems like a single leap.

At home in our homes, white-footed mice also build their nests elsewhere in hollow trees, stumps, brush piles, old squirrels’ or birds' nests. Their nests contain leaves, grass, feathers, shredded bark or moss, silky milkweed fluff, and cloth or paper. Once they have moved in to our human “hollow tree,” they seldom travel more than 160 feet from their comfortable, cozy quarters. They have amazing homing instincts. Captured mice that were let go two miles away have found their way back to their capture site. White-footed mice cache or store a winter supply of food in the fall near their nests.

Having found many white-footed mouse caches in my own home throughout the years, I often wondered or searched to identify the source of the seeds. These mouse caches help store food for winter use, and have been reported to contain several quarts of food. Some of the foods they prefer include acorns, maple seeds, pine seeds, black cherries, jewelweed, blueberries, violet seeds, curly dock, and beechnuts. Like squirrels, white-footed mice have cheek pouches in which they can transport food. In spring and summer they feed on fruit, beetles, snails, centipedes, moths, grasshoppers, crickets, caterpillars, cocoons, and other insects. They occasionally eat small birds or mammals. They can feed on wood, bark, stems, fruit, and flowers. They also eat roots of plants and fungi. White-footed mice also help spread fungi by eating and eliminating the spores. This is important in aiding the ability of trees’ to take up nutrients with help of the "mycorrhizal" associations formed with these fungi. It is nice to know that in addition to the entertainment they provide in my home, they have such a beneficial relationship to trees.

The most interesting thing I found in researching this white-footed creature is a very distinctive behavior. White-footed mice, when sensing danger, will drum with their feet on a hollow reed, dry leaf or other resonating material, producing a prolonged musical buzzing. Perhaps my new quest should be to discover the drumming sound of the white-footed mouse. I actually searched online to see if I could find a recording. Although I failed in that search, I learned once again that there is something to appreciate in every one of the creatures in which we share our homes.

.For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.