Originally aired during the week of November 1, 1999
Monday - What do you do when you're cold? Put on an extra sweater. Maybe turn up the thermostat or put another log on the fire. Pretty amazing strategies we've developed to stay warm. But what do you do in the winter if you're an animal? Well, lots of them do what lots of us do - they head south. I mean, they just clear out of here, as soon as the weather gets cold. Other animals stick close to home, trying to make it through the winter the best they can. Problem is, the cold and snow cover eliminate much of the food supply for months. Searching for scarce food during the few hours of daylight this time of year can burn off more calories than the animal can take in. So hibernation is one special strategy some animals use for winter survival. It involves lowering the body's temperature and slowing the heart rate to conserve energy during times of high stress and scarcity.
Many mammals are on the move this time of year - the increasing cold and fewer hours of daylight mean that it's time make plans for winter. Hibernation is a fact of life for many animals during this season, because the cold and snow cover eliminates much of the food supply for months at a time. Searching for scarce food during the few hours of daylight at this time of year can burn off more calories than the animal can possibly take in. Other animals migrate to warmer climes and new sources of food. Join us for a free evening program this Thursday called
Black Bears in the Backyard - and Other Mammals on the Move. Sponsored by the Silvio O. Conte National Wildlife Refuge, this talk by Vermont state biologist Kim Royer will tell us what's happening with mammal populations in the region this time of year.
Ever hear the saying "better let sleeping bears lie?" You haven't? Oh, right. That should have been "let sleeping DOGS lie." Well, letting sleeping bears lie is good advice, too. Black bears are commonly said to hibernate, but their winter experience is quite different from that of many smaller animals. First, a bear's body does not undergo the drastic changes like that of the red squirrel -- its temperature only drops about 9 degrees F below normal. Unlike squirrels, which may wake up every once and a while to eat from a carefully gathered food supply, bears remain inactive throughout the winter. Crawling into a shallow cave, a hollow log, or under a shelf of rock, the black bear burns the fat it builds up over the summer. But the bear's sleep state isn't nearly as deep as that of smaller mammals. So if you see one sleeping, leave it be.
All summer, woodchucks eat grass, clover, dandelions, goldenrod, garden vegetables (when they can get them), chickweed, insects... well, you get the picture. The woodchuck and many other small mammals take advantage of the abundant food supply to build up a thick layer of fat they use as an energy source during the winter months. The woodchuck is a true hibernator. When it settles into its underground winter den, its body temperature can drop to just a few degrees above freezing. Its pulse can go from 100 beats per minute, to five. So the woodchuck succeeds in reducing its energy needs to a minimum when food is scarce. Join us this evening at 7 at the Museum for a free program that explores what other mammals are up to during the late fall. Sponsored by the Silvio O. Conte National Wildlife Refuge, the talk is presented by Vermont state biologist Kim Royer.
We've been looking at ways local mammals stay warm in the winter. We've seen that some animals, mostly birds, head south. Monarch butterflies will migrate all the way to central Mexico before reaching their wintering grounds. For many animals that remain behind, huddling together can be an effective strategy to beat the cold. Animals like gray squirrels often share space with their kindred in order to generate body heat. According to naturalist Sy Montgomery, the temperature in a communal meadow vole nest can be as high as 50 degrees Fahrenheit even in January. Snow cover actually helps insulate these underground burrows from the cold air--in fact, snow is a better insulator than loose sand. Mammal fur also provides an insulating covering that helps the animal retain body heat, and many animals grow thicker fur in the cold months.
