February at a Glance: Pregnant female black bears give birth. Cubs begin to grow. Bears snug in their dens live off fat reserves, recycle waste and by-products into useful amino acids and heal many injuries. Other bears don’t hibernate at all; they just reduce their activities and make day beds so they can take periodic naps.

Dens turn into nurseries

Pregnant female black bears give birth to an average of two to three cubs weighing less than a pound; they wake up just long enough to lick the newborns clean before going back to sleep. At birth, cubs are covered in a coat of exceptionally fine, short hair. Their eyes and ear canals are closed, and their teeth have not yet emerged.

Bear cubs have a strong survival instinct and immediately start nursing on rich mother’s rich milk that’s 33% fat (human breast milk is only about 4% fat). Cubs make happy, humming noises while they suckle. Mother bears routinely feed and clean up after their cubs while still asleep, something any mother of a newborn can relate to. Read more about bear cubs.

Bears are busy sleepers

A denning adult bear can go as many as 200 days without eating, drinking or going to the bathroom. Bears live off the fat reserves they worked so hard over the summer and fall to acquire, recycling their waste and losing fat but not muscle. Bears also recycle calcium back into their bones and avoid the loss of bone density that affects people who are inactive for long periods of time. Many nagging injuries heal with little scarring and no infection.

Bear biologist Rich Beausoleil estimated the 9-year-old adult male bear (den opening pictured here) discovered snoozing away weighed about 280 pounds, and was doing great living off his fat reserves while denning over winter. 

Doctors hope that someday researchers will unlock this biochemical mystery and develop pharmaceuticals for humans that could induce a type of “human hibernation” that could help traumatic muscle and bone injuries heal more quickly, potentially cure osteoporosis, kidney failure and even improve space travel. Read more about hibernation.

Not all bears hibernate

Hibernation is driven by several factors, including the amount of daylight, temperatures and the availability of food. In Louisiana, Florida and Arizona, many black bears snooze for just a few days at a time; only pregnant females hibernate. Bears in poor condition without enough fat reserves may hibernate for a short time or not at all.

In areas where there is a bountiful year-round supply of human-provided foods, like garbage, pet foods and bird seed, some black bears no longer hibernate at all, so it’s important to be BearWise year round and help keep bears wild. Download our handy BearWise flyers and bulletins today.


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