Asian black bear
Asiatic black bears are diurnal, though they become nocturnal near human habitations. They may live in family groups consisting of two adults and two successive litters of young. They will walk in a procession of largest to smallest. They are good climbers of rocks and trees, and will climb to feed, rest, sun, elude enemies and hibernate. Some older bears may become too heavy to climb. Half of their life is spent in trees and they are one of the largest arboreal mammals. In the Ussuri territory in the Russian Far East, black bears can spend up to 15% of their time in trees. Asiatic black bears break branches and twigs to place under themselves when feeding on trees, thus causing many trees in their home ranges to have nest-like structures on their tops. Asiatic black bears will rest for short periods in nests on trees standing fifteen feet or higher. Asiatic black bears do not hibernate over most of their range. They may hibernate in their colder, northern ranges, though some bears will simply move to lower elevations. Nearly all pregnant sows hibernate. Black bears prepare their dens for hibernation in mid-October, and will sleep from November until March. Their dens can either be dug out hollow trees (sixty feet above ground), caves or holes in the ground, hollow logs, or steep, mountainous and sunny slopes. They may also den in abandoned brown bear dens. Asiatic black bears tend to den at lower elevations and on less steep slopes than brown bears. Female black bears emerge from dens later than do males, and female black bears with cubs emerge later than barren females. Asiatic black bears tend to be less mobile than brown bears. With sufficient food, Asian black bears can remain in an area of roughly 1–2 sq km, and sometimes even as little as 0.5–1 sq km.
American black bear
Throughout their range, habitats preferred by American black bears have a few shared characteristics. They are often found in areas with relatively inaccessible terrain, thick understory vegetation and large quantities of edible material (especially masts). The adaptation to woodlands and thick vegetation in this species may have originally been due to the American black bear having evolved alongside larger, more aggressive bear species, such as the extinct giant short-faced bear and the still-living grizzly bear, that monopolized more open habitats and the historic presence of larger predators, such as "Smilodon" and the American lion, that could have preyed on American black bears. Although found in the largest numbers in wild, undisturbed areas and rural regions, American black bears can adapt to surviving in some numbers in peri-urban regions, as long as they contain easily accessible foods and some vegetative coverage.