Black Bear Hibernation

“Do Black Bears Really Hibernate?” The N.C. Wildlife Resources Commission receives this question often from the public. Usually, this question is prompted after people have observed bears, or pictures of bears, that are active during the winter months. The short answer is yes, black bears hibernate in North Carolina, and throughout North America (even in Florida). Our answer is sometimes followed up with responses such as “well, bears aren’t true hibernators” or “it’s not hibernation, it’s torpor.” The hibernation process black bears go through is actually truly unique, earning them the well-deserved nickname as “Super Hibernators.”

What is Hibernation?

The hibernation process varies by mammal species, but a simple way to understand hibernation is that it is a physiological process in which a mammal reduces its metabolism to survive during a time of year when natural food supplies are scarce and/or temperatures are low.

What does hibernation look like for black bears?

Several physiological changes occur in black bears, including the lowering of their metabolism, heart rate, breathing, and oxygen consumption. Unlike bats and rodent species, such as groundhogs, who drop their body temperature close to freezing (thus their nickname as “true hibernators”), black bears only drop their body temperatures by 10-15 degrees. As a result, black bears can be somewhat wakeful sleepers and will abandon their den if seriously disturbed whereas many rodents are so deep in hibernation that they can be handled without waking.

Why are black bears called Super Hibernators?

Most hibernating mammals, such as ground hogs and bats, arouse from hibernation periodically to feed, urinate, and defecate. But black bears can remain stationary for longer periods than the “true hibernators” without feeding or eliminating waste, as bears can process the build-up of waste that would kill most animals if they did not arouse from hibernation to handle normal bodily functions. Furthermore, despite the periods of inactivity, black bears do not suffer from bone or muscle loss; they can exit their winter dens strong and healthy.

But do all black bears hibernate in North Carolina?

Based on 40+ years of research, a vast majority of North Carolina black bears hibernate. Females typically hibernate longer than males and North Carolina’s bears hibernate for a shorter time periods than in more northern climates.

But I see black bears active in the winter, so they aren’t hibernating?

Black bears in North Carolina can go into hibernation as early as mid-October and as late as January. These same bears may exit hibernation as early as February and as late as April. This results in the possibility of bear sightings and vehicle-bear collisions in all months and the misconception that North Carolina’s black bears do not hibernate.

However, hibernation in black bears is largely driven by food supplies and, while natural foods remain scarce in the winter, there is an increasing abundance of human-provided foods (e.g., unsecured garbage, bird feeders, purposeful feeding of bears) available year-round). With the availability of human-provided foods in winter, there is less need for a black bear to hibernate for any length of time.

For more information on living responsibility with black bears and keeping them wild, please visit BearWise.org.

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