Den



Black bears choose a denning site with the coming of cold weather. Dens are usually hollow stumps, tree cavities, or wherever there is shelter. Bears in the Smokies are unusual in that they often den high above the ground in standing hollow trees. Bears do not truly hibernate, but enter long periods of sleep. They may leave the den for short periods if disturbed or during brief warming trends. ([])


 * Black bears may den in a hollow standing live or dead tree, under a fallen tree, in a rock cave, or in a burrow dug by the bear (often under roots or logs).
 * In southern areas, they may den in a nest of leaves and grass on the ground. Even in some northern areas, they may build large nests out of conifer boughs.
 * Black bears usually line the den with leaves, grass, lichen, rotten wood or ferns and may close the entrance with leaves or grass, which both camouflages the entrance and helps in heat retention.
 * Dens are quite small, usually just large enough to contain the bear.
 * In general, black bears choose a different den from year to year.
 * The oxygen level inside the den may fall as low as 15.9% if snow crusts over the den surface; this does not affect the bear's survival. ( [] )