Asian black bear
Along with sun bears, Asiatic black bears are the most typically used species in areas where bears are either used in performances or as pets. Asian black bears have an outstanding learning ability in captivity, and are among the most common species used in circus acts. According to Gary Brown:
American black bear
The hibernating American black bear does not display the same rate of muscle and bone atrophy relative to other nonhibernatory animals that are subject to long periods of inactivity due to ailment or old age. A hibernating American black bear loses approximately half the muscular strength compared to that of a well-nourished, inactive human. The bear's bone mass does not change in geometry or mineral composition during hibernation, which implies that the bear's conservation of bone mass during hibernation is due to a biological mechanism. During hibernation American black bears retain all excretory waste, leading to the development of a hardened mass of fecal material in the colon known as a fecal plug. A special hormone, leptin, is released into the bear's systems to suppress appetite. The retention of waste during hibernation (specifically in minerals such as calcium) may play a role in the bear's resistance to atrophy.
The body temperature of the American black bear does not drop significantly, like other mammalian hibernators (staying around ) and they remain somewhat alert and active. If the winter is mild enough, they may wake up and forage for food. Females also give birth in February and nurture their cubs until the snow melts. During winter, American black bears consume 25–40% of their body weight. The footpads peel off while they sleep, making room for new tissue.