Hibernation

Once a black bear begins hibernating, it can doze for many months with a body temperature of 88°F or higher. By contrast, the body temperature of smaller hibernators such as marmots, chipmunks, and ground squirrels may drop below 40°F. These creatures must awaken every few days, raise their body temperatures to summer levels, eat stored food, and excrete wastes.

hibernating black bears ||   || Bears can go on slumbering because they can retain body heat. This, in turn, enables them to cut their metabolic rate in half. In the early fall, their heart beat 50 times a minute for most of each night. By December, when the bear was deep in hibernation, its sleeping heart rate had slowed to as few as eight beats a minute.
 * [[image:http://www.pbs.org/wgbh/nova/satoyama/images/hiber_denbear.jpg width="250" height="169" caption="bear in den" link="http://www.pbs.org/wgbh/nova/satoyama/hibernation_04.html"]]

Black bears keep their heads and torsos warm enough that they can wake if disturbed, though some may take awhile to do so. In a 1981 article in //Natural History,// Rogers told of the time he accidentally fell onto a six-year-old female in her den. Even though her cub bawled, she didn't wake up for at least eight minutes. On the other hand, some individuals can revive disconcertingly quickly. Rogers again:


 * This has led some biologists to differentiate between the hibernation of, say, jumping mice and the "winter lethargy" of bears. Ours is not to quibble, however, and for the purposes of this article, sleeping through the winter—to whatever degree—will be referred to as hibernation.


 * Citation added:** "NOVA Online | Japan's Secret Garden | Secrets of Hibernation." //PBS//. Peter Tyson, Dec. 2000. Web. 03 Dec. 2009. .

Edited by: CMJ1988