About Bear Hibernation
A note on winter adaptive behavior for bears, from Elizabeth Wasserman, National Park Ranger, Lake Clark National Park & Preserve:
While our community friends "down under" in the southern hemisphere are embracing the warmth of spring, we in the north are making adjustments as winter closes in. With less than seven hours of daylight now at my Alaskan home, I’m lighting the darkness with candles and warming myself with extra layers of clothing and bumping up the thermostat. We humans make changes to our environment to fit our needs.
Bears don’t have that luxury. They have to make changes in their behavior in response to what the environment presents. Of the eight species of bears in the world,* only the four northern species (polar, brown, Asiatic black and American black bears) have to adapt to extreme changes in weather conditions and food availability. Scientists give winter adaptive behavior different names; hibernation, winter dormancy, winter sleep, walking hibernation. Basically, bears employ an energy conservation strategy to help them survive in the particular environments they inhabit. They lower their heart rates, their metabolism rates, and their body temperatures somewhat and wait out the winter season, living off their body fat until conditions change where they are.
Most hibernation research has been done on the American black bear and much of what we’ve learned about bear hibernation has come from these studies. However, it’s hard to make generalizations when it comes to bear behavior in any form. Wayne Lynch, writing in Bears: Monarchs of the Northern Wilderness (Seattle, 1993), put it this way:
If you watch enough bears for a long enough time, you see them behave in ways you have never seen before…bears have a rich behavioral repertoire. They are intelligent, adaptable creatures that readily modify their behaviour in response to the many vagaries of their environment. Thus, den emergence behaviour. and all other behavior in bears often varies between individuals, from season to season and from region to region. This behavioral plasticity is at the heart of the bears' success in surviving.
*See http://www.bearbiology.com/iba/bears-of-the-world.html for a description of each of the eight bear species.
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Learn More about Bears
Grizzly Bears
Brown bears dig dens for winter hibernation, often holing up in a suitable-looking hillside. Females give birth during this winter rest and their offspring are often twins. Learn more about these awe-inspiring giants in National Geographic's Grizzly Bear Profile.
Polar Bears
Do polar bears hibernate? Find the answer at Polar Bears International.
View the archived Polar Bear Cam Q & As from Nov. 1 and Nov. 7
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Polar Bear Discussion 1 »
Polar Bear Discussion 2 »