Black Bear Prepare to Hibernate as Weather Gets Colder

November 14, 2011; 8:00 AM ET
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Photo of a black bear cub in a tree courtesy of Photos.com.

As the temperatures drop, black bear in the United States are foraging for food to build fat to sustain themselves throughout the winter months.

In Central Pennsylvania, residents have reported that bird feeders have been ripped out of trees by the black bear. Another favorite foraging activity for bear is to rip open bags of trash and search the contents for anything edible.

During the late fall and early winter, it is best to remove and store bird feeders if you live in an area where bear are populous.

Another helpful way to prevent bear damage around your property is to store your garbage in a locked shed and put it out to be picked up as close as possible to trash pickup.

Bear throughout the U.S. hibernate on different time schedules, according to bear.org. In Ely, Minn., and areas in the central and western parts of the U.S., bear tend to begin hibernation in September or October.

In states in the eastern parts of the U.S., the bear don't usually begin their hibernation until late November or early December.

Bear in the southern U.S. may not hibernate at all due to the warmer weather and food available all winter long.

Bear.org reports that even when the bear in Minnesota are offered food later in the fall, they abandon the food and begin their hibernation on time.

During hibernation, the bear go through five different stages.

First Stage

The spring until midsummer or fall is the time when the bear are in their normal activity. If food and water are available, the bear will consume about 5,000 to 8,000 calories each day. If they are unable to consumer enough food and water during this time, they will be unable to successfully hibernate in the winter.

Second Stage

This stage is known as hyperphagia. During this stage, bear eat and drink excessively as they build up fat stores for hibernation. When food and water are plentiful, black bear have been know to eat as many as 15,000 to 20,000 calories a day. The need large amounts of water to process the food and flush nitrogenous waste from their bodies.

Third Stage

After they go through hyperphagia, it is time for their fall transition. During this time, their metabolic processes change as they prepare to hibernate. Their heart rate slows from the normal 80-100 beats per minute to about 50-60 beats per minute. During sleep, their rate is about 22 beats per minute. The normal beats of a sleeping bear are between 66-80 per minute. The bear continue to drink, but will start to eat less. As they prepare to hibernate, they can rest as much as 22 hours a day.

Fourth Stage

Hibernation begins. The bears' breathing slows to about half of their normal rate. They take a breath only once every 45 seconds. Their heart rates slows even more. It can drop periodically to between eight and 21 beats per minute. They burn about 4,000 calories per day. They do not eat, drink, urinate or defecate during hibernation.

Fifth Stage

This stage is known as walking hibernation. During the first two to three weeks after the bear leave their hibernation den, their metabolic processes return to normal levels. During this time, they will continue to eat and drink less than they do in the summer months. Their bodily waste processes are also reduced. Once this time is past, the bears resume their normal summer activity.

Bear that are in hibernation can be hard to wake if they are disturbed. The bear that are in warmer climates may not be in as deep hibernation as bear in colder areas. Female bear often give birth in the den during the winter months. The mother bear tend to be in a lighter state of hibernation as they awaken to care for their young.

Should you stumble upon a hibernating bear, the best thing to do is to quietly leave the area.

This photo of a black bear is courtesy of NPS.gov.

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