What kind of den does a black bear use?
Black bears occur throughout a wide range of habitats and climatic conditions in North America. Denning (and hibernation) is probably a behavioral response which allows the bears to survive unfavorable winter weather and a periodic lack or scarcity of food. A reasonable hypothesis thus proposes that black bears select dens to facilitate energy conservation, and hence survival of the bears and their young. Some initial data suggest this to be false; however, there is not enough information to draw a firm conclusion. Survival risks to denned bears may be related to factors other than poorly insulated dens. Bears will utilize many materials or sites to create a den, including open nests, brush piles, fallen trees, rock piles, excavations, hollow trees, and human structures. Bears will often, but not always, make nests of grasses, twigs, or other material within the den. Regional variations are apparent and have been presumed to relate to energy needs (but see above). The sex and age of th
