Nature Watch
August 30, 2008
By Susan Benson,
CNHM Director of Education
Have you noticed mallards and other ducks migrating? Or have you run into a chipmunk scurrying across the ground, cheeks bulging twice the width of its head with hazel nuts? Or your pet cat, dog, or rabbit beginning to grow a thicker coat as the days grow shorter?
It is only early September, but winter is coming, and animals have strategies for coping. Breeding has been timed so that offspring can grow and develop enough to survive their first winter. These young have time now to grow their first winter coat. Mothers who have lost weight when nursing now have time to improve their condition before winter.
Some animals leave the area through migration. Land animals have a more difficult time with migration because walking is much less efficient than flying. For those animals that stay, there are other options. Body size determines where the animals that stay end up spending the winter. A moose, for example, with its long legs, can walk through the deep snow, but smaller animals cannot, so they have to prepare to spend winter either under the snow or in areas with little or no snow. The big brown bat will soon begin searching for a winter habitat—that may be in an outbuilding or your attic. Keep a lookout for any of the signs of animal preparation for the coming cold season.
The trigger for the change in animal physiology and behavior is the photoperiod—the relative length of light and darkness during a given day. With the relative increase in darkness, many big mammals gain fat between their internal organs and under the skin. In preparation for their long winter sleep, or hibernation, woodchucks grow enormously fat toward the end of the summer. During autumn, black bears eat more than usual to gain body fat to sustain them through their winter “slumber.” Bears do not truly hibernate, but rather fall into a deep sleep from which they can awaken quickly. During late summer, a bear will eat five pounds of food per day in preparation for winter. Imagine eating five pounds of acorns! Northern small mammals gather so-called brown fat, which generates heat very effectively. Black bears and other hibernating animals maintain this same brown fat because it has the ability to dissipate stored energy as heat.
The fur of foxes, badgers and squirrels thickens to allow them to keep their body temperature constant during the cold weather. The snowshoe hare begins growing its white fur coat, beginning with its ears and tail; the total color conversion takes about 10 weeks. The short-tailed weasel also changes its fur coat to white with the exception of the black-tipped tail, which is thought to be an adaptation so that when the weasel is being chased, the pursuer will focus on black tail tip and miss catching the weasel.
White-tailed deer are affected as well; in late summer, a gland in their brains stimulates the reproductive organs. In bucks, hormones increase and the antlers harden and the velvet is shed. The period of hard antler lasts from early September to early February. We are familiar with bucks rubbing against saplings and smaller trees, removing the outer bark, and exposing the tree’s cambium underneath. The bucks then rub the cambium with their foreheads, where a scent gland is located, leaving a sign of their presence left behind for others to discover.
Some mammals, like squirrels, mice, and beavers, gather extra food in the fall and store it to eat later. Squirrels store their food, either in centralized heaps, or buried in the ground, sometimes with just one nut or acorn in each hole. Squirrels will cover their hiding place with care; these caches are usually found within 75 feet of where the squirrel found the nut or seed. When the snow cover thickens, the squirrel digs out the hiding places, and after having eaten some of the seeds, hides them again, this time closer to the snow surface. Some squirrels even store fungi in the branches of the trees. In a good fungus year, one might see dried and darkened mushrooms hanging on the lower branches of trees. During the late summer and fall, beavers also put food away, storing branches at the bottom of their ponds in preparation for winter.
Become a phenologist! Create your own backyard winter habitat by constructing a pile of logs, rocks or leaves—ideal winter lodging for mice, shrews, rabbits, toads, frogs or other small animals. Enjoy watching the outdoor action as our mammal neighbors harvest nature’s fall treats.
Nature Watch is brought to you by the Cable Natural History Museum. 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 in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
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Saturday, August 30, 2008
Wednesday, August 20, 2008
Glacial Erratics
Nature Watch
August 20, 2008
By Susan Benson,
CNHM Director of Education
On a stroll through the backwoods of northwest Wisconsin, you may come across an unusual sight — a large rock, perhaps sitting all by itself in a meadow or on the forest floor. There may be no other rocks in sight. How did this one get here? You’re probably looking at a glacial erratic, a piece of rock that may have been transported great distances by the ice sheets that covered the region long ago. One long-distance champion is an erratic composed of solid native copper, probably originating from the Lake Superior region along the Upper Peninsula of Michigan, that was moved by glacial ice more than 600 miles to southern Illinois.
Glacial erratics can be any size from small pebbles to huge boulders. Most of them appear worn and rounded, sometimes including beveled or faceted surfaces. During the course of their journey, the rocks were jostled against other erratics or scraped against underlying bedrock, rounding off corners and planing smooth surfaces. Glacial transport also fractured some boulders, resulting in sharper edges.
Transportation by glacial ice produced other unique features, the most easily observed of which are glacial striations, series of parallel lines or grooves gouged across the rock face or inscribed on the underlying bedrock surface. These glacial furrows were produced when an erratic, frozen firmly in slowly moving ice, scraped against another erratic or against the bedrock surface over which the glacier was moving. These glacial striations can be used to identify the direction of ice movement.
The composition of glacial erratics can reveal their point of origin and give clues about the direction of ice movement. For example, a string of erratics of similar composition might be observed across a broad region. These are referred to as “boulder trains,” series of erratics that originated from the same source. Boulder trains appear as long lines or fans of erratics extending outward from their source in the direction of ice flow.
On your next hike, keep your eyes open for glacial erratics. Each one has a story to tell!
Nature Watch is brought to you by the Cable Natural History Museum. 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 in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
August 20, 2008
By Susan Benson,
CNHM Director of Education
On a stroll through the backwoods of northwest Wisconsin, you may come across an unusual sight — a large rock, perhaps sitting all by itself in a meadow or on the forest floor. There may be no other rocks in sight. How did this one get here? You’re probably looking at a glacial erratic, a piece of rock that may have been transported great distances by the ice sheets that covered the region long ago. One long-distance champion is an erratic composed of solid native copper, probably originating from the Lake Superior region along the Upper Peninsula of Michigan, that was moved by glacial ice more than 600 miles to southern Illinois.
Glacial erratics can be any size from small pebbles to huge boulders. Most of them appear worn and rounded, sometimes including beveled or faceted surfaces. During the course of their journey, the rocks were jostled against other erratics or scraped against underlying bedrock, rounding off corners and planing smooth surfaces. Glacial transport also fractured some boulders, resulting in sharper edges.
Transportation by glacial ice produced other unique features, the most easily observed of which are glacial striations, series of parallel lines or grooves gouged across the rock face or inscribed on the underlying bedrock surface. These glacial furrows were produced when an erratic, frozen firmly in slowly moving ice, scraped against another erratic or against the bedrock surface over which the glacier was moving. These glacial striations can be used to identify the direction of ice movement.
The composition of glacial erratics can reveal their point of origin and give clues about the direction of ice movement. For example, a string of erratics of similar composition might be observed across a broad region. These are referred to as “boulder trains,” series of erratics that originated from the same source. Boulder trains appear as long lines or fans of erratics extending outward from their source in the direction of ice flow.
On your next hike, keep your eyes open for glacial erratics. Each one has a story to tell!
Nature Watch is brought to you by the Cable Natural History Museum. 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 in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Wednesday, August 6, 2008
Redwing Blackbirds
Nature Watch
August 6, 2008
By Susan Benson,
CNHM Director of Education
“Today is August first, and I woke up to the terrific “chatter” of what sounded like hundreds or thousands of birds. Were they starlings in my back yard? Robins? Then it hit me – the red-winged blackbirds were already congregating. For the past three years, I’ve seen these birds in large numbers, always in early August, ensconced in my large pines, singing merrily. Am I lucky enough to have my backyard on their migratory pathway? Is there some other reason? The curious scientist in me had to explore.”
– From my phenology journal
Fall migration in the northwoods for red-wings begins in mid-July as birds disperse from their nesting areas to form loose flocks. The numbers gradually build through August reaching peak abundance during September 10-25. During this period, roost flocks ranging up to 50,000 individuals can be observed. Most fall migrants have departed by early November with a few stragglers hanging around through December. Some of these roosts will also include other bird species such as European starlings. Here we are in the sweet summer heat and weather, and I’m saying a fond farewell to our red-winged blackbirds!
When next spring comes around, the male red-wing is often one of the first migrants to arrive in our area. The male fiercely defends his territory during the breeding season, spending more than a quarter of all daylight hours in territory defense. He keeps other males out of his territory and defends the nests from predators. Humans wearing a red jacket into a marsh in the spring, should not be surprised to be attached by this fierce defender. Birders have seen the males chase crows, great blue herons, deer, and other birds as well. When singing to defend their territory or to attract a female, the male fluffs the red decoration and half-spreads his wings to show off the red and look his best. The red-winged males can also have up to fifteen different females making nests in his territory. A high percentage of territorial males have more than one female but, up to one-half of the young in "his" nests do not belong to the territorial male, having been sired by neighboring males.
We can continue to enjoy this bird species, as the red-winged blackbird is possibly the most abundant bird in North America. If you have your own red-wing observations to share or other interesting observations, please email the Museum at info@cablemuseum.org.
Nature Watch is brought to you by the Cable Natural History Museum. 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 in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
August 6, 2008
By Susan Benson,
CNHM Director of Education
“Today is August first, and I woke up to the terrific “chatter” of what sounded like hundreds or thousands of birds. Were they starlings in my back yard? Robins? Then it hit me – the red-winged blackbirds were already congregating. For the past three years, I’ve seen these birds in large numbers, always in early August, ensconced in my large pines, singing merrily. Am I lucky enough to have my backyard on their migratory pathway? Is there some other reason? The curious scientist in me had to explore.”
– From my phenology journal
Fall migration in the northwoods for red-wings begins in mid-July as birds disperse from their nesting areas to form loose flocks. The numbers gradually build through August reaching peak abundance during September 10-25. During this period, roost flocks ranging up to 50,000 individuals can be observed. Most fall migrants have departed by early November with a few stragglers hanging around through December. Some of these roosts will also include other bird species such as European starlings. Here we are in the sweet summer heat and weather, and I’m saying a fond farewell to our red-winged blackbirds!
When next spring comes around, the male red-wing is often one of the first migrants to arrive in our area. The male fiercely defends his territory during the breeding season, spending more than a quarter of all daylight hours in territory defense. He keeps other males out of his territory and defends the nests from predators. Humans wearing a red jacket into a marsh in the spring, should not be surprised to be attached by this fierce defender. Birders have seen the males chase crows, great blue herons, deer, and other birds as well. When singing to defend their territory or to attract a female, the male fluffs the red decoration and half-spreads his wings to show off the red and look his best. The red-winged males can also have up to fifteen different females making nests in his territory. A high percentage of territorial males have more than one female but, up to one-half of the young in "his" nests do not belong to the territorial male, having been sired by neighboring males.
We can continue to enjoy this bird species, as the red-winged blackbird is possibly the most abundant bird in North America. If you have your own red-wing observations to share or other interesting observations, please email the Museum at info@cablemuseum.org.
Nature Watch is brought to you by the Cable Natural History Museum. 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 in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
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