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Black Bear Dens
Bears In Winter
These are two very young black bear cubs with the
mother bear in the winter den.
Bear babies keep warm by sleeping on their mother's fur,
and from her breath warming the den.
Photography by Kate Marshall.
Frustrated with other bear programs that don't really show you
what is going on in a bear's den? Big build up, then not so much?
Then this is a must see for you!
See well-lit scenes of tiny 4-day-old black bears in the winter den
with their mother. See how they find their dinner before their little eyes
are open, see how their mother cares for them in their warm den
while it is snowing outside! Very rare and unusual film of
tiny newborn bears! After that, watch little black bears grow up wild
and see them interact with their siblings and with their mother.
Footage of baby bears with their mother so beautiful,
you just may shed a tear when you see it!
Winter is the first season in the life of a black bear. All black bears are born in winter, usually in late January or early February. The mother bear has made a nest and has settled in for the cold months of winter. This is called "denning." The bear nest is called a "den."
A black bear's winter den can be as simple as a dirt scrape, as cozy as the hole under an overturned tree's roots, or as secluded as the inside of a one-hundred-foot-tall hollow tree trunk with the entrance in the top of the tree. Sometimes a mother bear will choose a warm dark cave in which to have her babies. Caves can have walls of earth and dirt, or walls of tree roots, or walls of stone.
The student with a Summer Science Camp at Innoko National Wildlilfe Refuge
in Alaska is measuring the entrance to a black bear den.
Photo Copyright U.S. Fish & Wildlife Service, Innoko NSR - 034
Alaska Image Library - Used with Permission
Terms of Usage Apply
Bears have been seen hibernating through the winter in only a shallow dirt scrape on the ground, with some leaves under and on top of the bear. The bear will sleep through winter weather, and the snow on top of the bear will actually act as insulation.
Sometimes a bear may make a winter den in the top of a hollow tree. When lightning strikes a tree and the top of the tree is dead, rain and the elements continually work on scooping out the interior of the tree. A bear will climb the tree and go down into the hollow. She will curl up in there and have her babies there. It may rain or snow on the bear from above, but the water will drain through the porous tree, and her fur will insulate her against the cold. Hollowed out bear trees may be as high as a hundred feet, especially in some areas of the Smoky Mountains.
The bottom of the bear's den or nest is covered with materials that she has brought in for her bed. She will spend time bringing in mouthfuls of bedding, or pushing it in with her large paws. These bedding materials can be piles of leaves, grass, sticks, small branches, pine cones, straw, plants, leaf litter from the forest, etc. A bear can spend up to a month gathering den materials and putting them inside the selected den.
If the adult is a female with year-old cubs, the cubs all assist in gathering den materials. This seems to be instinctual. Older cubs who, for some reason, no longer have a mother around, still know how to make a den, even though they have not been taught how to do it. Even younger orphaned cubs who are without their mother in late summer know how to make a leaf and grass nest at the base of a safety tree.
Bears sometimes make their dens in odd places. We have seen photos taken in the Pacific Northwest of a black bear denning in an eagle's stick nest, very high up in the top of a tree. Sometimes a bear will den underneath a back porch of a house, in a crawl space, in a storage building, or on top of a covered hot tub. Bears will den any place they think is protected and warm and safe, and sometimes it may be near a house or garage.
These are two very young black bear cubs
with the mother bear in the winter den.
Newborn bears sleep a lot in the den, and wake up only to nurse.
Photography by Kate Marshall.
Adult bears will curl up into a ball inside the den to keep warm. Since the inside of a bear's den is about the same temperature as the outside forest in winter, the bear's thick fur helps keep the bear warm. A bear's winter fur is much more dense than at other times of the year. The inside of the den is kept warmer by the bear's body heat and breath.
Bear dens are very special secret bear places, and they are difficult to see by humans. If you should ever find one by accident, leave the area immediately. The bears must not be disturbed. Historically, early American Native Americans knew where bear den sites were, and so winter was the time of year when they would have their bear hunt which would supply them with hides, meat, and grease. Sleeping bears were easier to approach than bears that were alert.
In the autumn, female bears may have to eat even more than other solitary adult bears, because they have to have enough fat to get them through the winter and enough calories to produce fat-rich bear milk for their babies when they are born.
Newborn bears cannot see, and must find the milk by smell,
and by the mother guiding them.
Photography by Kate Marshall.
It is quiet in a bear's den if the bear is alone. It is noisy in the den if the bear has babies. In the beginning, the 10-ounce babies wake up every 10 minutes to nurse. The length of time between feedings becomes longer as the babies begin to grow and get older. Later they will nurse every 15 minutes, then every 20 minutes, then every 30 minutes. The mother bear can sleep only when the babies are sleeping. Baby black bears are very noisy in the den. They make a humming sound when they are nursing, and sometimes they cry. They are so tiny that she must be awake to push them back when they stray, to put them on the teat, to wash them, and to watch them constantly.
Bears make very good mothers and take care of all of their babies. A mother bear will even take care of another bear's baby if it is introduced into the den. A mother bear gets very little sleep once the baby bears are born. As they grow older and stronger, then she can sleep more.
Baby bears in the den will sleep nestled in their mother's fur, sometimes sprawling spread-legged across her tummy, waking up very near the teat. Baby bears also like to sleep tucked up under their mother's chin. She keeps them very warm, and watches them closely.
This is a closeup of the paw of a sleeping baby black bear -
it is resting its paw on the mother bear's nose.
This was shot inside of a bear's winter den.
Notice that bears are born with claws.
Photography by Kate Marshall.
If the bear is not a female that will be having babies, the bear goes into the winter den alone, and stays alone. Black bears recycle their waste so that they can stay inside of the den all winter if they need to. A bear in a den does not eat, drink, urinate, or defecate.
Since there is no food for a bear to eat in the winter months, denning and semi-hibernation are valuable survival skills that a black bear has. The lack of food is the real reason that a bear dens. A bear can make it through the winter if it has eaten a lot during the year. This is the reason why bears are so focused on eating more food than they really need: they are always instinctively trying to get fat enough to make it through the winter. They don't think about it, they just do it. It just comes naturally.
Black bears come out of their winter den when their babies are big enough to walk and run and explore their surroundings, and when the mother must find food after a long rest. In the spring, cubs will continue to nurse on bear milk.
"Cinnamon Brown" Black Bear with 3 spring cubs
on a river bank, recently having come out of their winter den.
Copyright Yellowstone National Park, Photographer unknown.
Here is a wonderful article pertaining to black bear hibernation submitted to KMG for CoveBear.com. It gives us even more information about this fascinating subject:
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WHAT’S IN A NAME? Hibernation Means Different Things to Different Animals
by Mark D. Jones
Black Bear Project Leader
North Carolina Wildlife Resources Commission
Copyright April, 1999
“Do bears really hibernate”? This is a question I often hear from the general public and even other wildlife biologists. When I answer yes, many people next ask, “do they really hibernate in North Carolina, or is this just a northern behavior”? Well, the answer is that bears hibernate throughout North America and certainly in North Carolina. However, the process is very different from what is considered “normal” hibernation exhibited by rodents and bats.
To understand this issue, we first need to define the process of hibernation. In its simplest definition, hibernation is a specialized reduction in metabolism brought about by low food availability and/or low temperatures. Several body changes can occur during hibernation. These include lower heart rates, constriction of blood vessels, suppressed shivering, reduced breathing, and lower oxygen consumption. Another process common during hibernation is known as adaptive hypothermia. This is a process by which an animal lowers its body temperature in order to conserve energy. Different species may utilize different degrees and combinations of the previously mentioned metabolic processes. Many species of rodents and bats drop their body temperatures very dramatically, some to near freezing. Bears on the other hand only drop their body temperatures by 10-15 degrees in most cases. As a result, bears are somewhat wakeful sleepers and are capable of abandoning a den if seriously disturbed whereas many rodents are so deep in hibernation that they can be handled without waking.
Most hibernating mammals, such as woodchucks (ground hogs to most North Carolinians), must arouse from hibernation periodically to feed, urinate, and defecate. Herein lies the main difference in bear and rodent hibernation. Bears have the ability to remain stationary for longer periods than rodents without feeding or eliminating waste. In northern areas of the U.S. and Canada, bears hibernate as long as 8 months without moving from their den. In the South, bears exhibit the same characteristics, only for shorter time periods. The build-up of waste that bears somehow process would kill most animals if they did not arouse from hibernation to handle normal bodily functions. Furthermore, the long periods of inactivity would result in degradation of bones and muscles for non-hibernating animals. Bears however exit their winter dens strong and healthy after long periods of inactivity. Whatever you call the process in bears, it is a truly remarkable physiological achievement. Medical doctors are attempting to understand bear hibernation better in order to help patients suffering from kidney dysfunction and bone degradation.
What about bears in North Carolina? Based on hundreds of radio-collared black bears studied across the state, we know that the vast majority of our bears hibernate. Females typically hibernate longer than males. North Carolina’s bears just do it for shorter time periods than their northern cousins. Bears studied in eastern North Carolina by radio-telemetry entered dens as early as November and as late as January. These same bears exited dens as early as February and as late as April. This results in the possibility of bear sightings and roadkills in all months and the misconception that coastal bears do not hibernate. Only human disturbance interrupts these periods of hibernation in North Carolina’s bears.
Female bears give birth during hibernation and nurse their cubs through a period of helplessness. The female “hibernates” throughout the entire process, and unless disturbed, she will not leave the den until she brings her cubs out of the den in the spring. By that time, the cubs can walk and follow the mother as she feeds.
The next time someone says black bears do not “hibernate”, please tell them that whatever you wish to call the process, bears do enter a long period of physical inactivity and exhibit some amazing physiological responses to low food availability and temperatures. In many ways, their ability to hibernate for long periods without feeding or eliminating waste is more advanced and remarkable than what has been considered “normal” hibernation involving periodic arousal to move about and feed.
* * *
Reprinted with Permission to KMG at CoveBear.com
AMERICAN BLACK BEAR DVDs
Click on bears to read about these award-winning programs!
The Gold Classic Telly Award, The 30th Annual Telly Awards, 2006
Category: Videography / Cinematography
The Bronze Telly Award, The 27th Annual Telly Awards, 2006
Category: Nature & Wildlife Documentary
Silver Remi Award, The 38th WorldFest International Film Festival, 2005
Category: Ecology-Environment-Conservation Documentary
Bronze Remi Award, The 36th WorldFest International Film Festival, 2003
Category: Nature & Wildlife Documentary
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