Bear hibernation facts

By news@duluthnewstribune.com

February 09, 2013 11:00 PM

Here are some facts about bear hibernation from Dave Garshelis, bear project leader for the Minnesota Department of Natural Resources.

Hibernation defined: A physiological state of greatly depressed metabolism used to conserve energy during extended periods of food scarcity and/or cold. Black bears are considered hibernators.

Minnesota bears enter dens in September and October. They leave dens in late March to mid-April.

A bear's body temperature drops from 99 to 91 degrees Fahrenheit. It drops no lower than that because bears, in their easily accessible dens, must be able to defend themselves against predators.

Heart rate is reduced from 80 beats per minute to less than 20 beats per minute and is timed with breathing. Gaps between beats last up to 14 seconds.

Metabolism is reduced to one-fourth of summer levels.

Bears don't stand during their entire hibernation but do change body positions. Bears do not arouse during hibernation, but females give birth in January and move around to nurse.

Before hibernating, bears feed heavily. Fat reserves can reach 50 percent of body mass by time of hibernation, but are more commonly about 33 percent.

Bear hibernation facts

Here are some facts about bear hibernation from Dave Garshelis, bear project leader for the Minnesota Department of Natural Resources. Hibernation defined: A physiological state of greatly depressed metabolism used to conserve energy during exten...