The Asian Black Bear

Asian Black Bear :: WLR :-The Asian black bear (Ursus thibetanus), also known as the moon bear or white-chested bear is a medium-sized species of bear, largely adapted for arboreal life, which occurs through much of southern Asia, Korea, northeastern China, the Russian far east and Honshū and Shikoku islands of Japan. It is classed by the IUCN as a vulnerable species, mostly due to deforestation and active hunting for its body parts. The species is morphologically very similar to some prehistoric bears, and is thought by some scientists to be the ancestor of other extant bear species. Though largely herbivorous, Asian black bears can be very aggressive toward humans, and have frequently attacked people without provocation. The species was described by Rudyard Kipling as "the most bizarre of the ursine species."

Biologically and morphologically, Asian black bears represent the beginning of the arboreal specialisations attained by sloth bears and Sun bears, though these traits are not as maximally attained in Asian black bears. Asian black bears have karotypes nearly identical to those of the five other ursine bears, and, as is typical in the genus, they have 74 chromosomes. From an evolutionary perspective, Asian black bears are the least changed of Old world bears, with certain scientists arguing that it is likely that all other lineages of ursine bear stem from this species. Scientists have proposed that Asian black bears are either a surviving, albeit modified, form of Ursus etruscus, specifically the early, small variety of the middle Villafranchian or a larger form of Ursus minimus, an extinct species which arose four million years ago. With the exception of the age of the bones, it is often difficult to distinguish the remains of Ursus minimus with those of modern Asian black bears.

Asian black bears are reproductively compatible with several other bear species, and have on occasion produced hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, Florida was thought to have been the offspring of an escaped female Asian black bear and an American black bear, and Scherren's Some notes on hybrid bears published in 1907 mentioned a successful mating between an Asian black bear and a sloth bear. In 1975, within Venezuela's "Las Delicias" Zoo, a female black bear shared its enclosure with a spectacled bear, and produced several hybrid descendants. In 2005, a possible black bear/sun bear hybrid cub was captured in the Mekong River watershed of eastern Cambodia. An Asian black bear/brown bear hybrid, taken from a bile farm, is housed at the Animals Asia Foundation's China Moon Bear Rescue as of 2010.

Asian black bears are similar in general appearance to brown bears, but are more lightly built and more slender limbed. The skulls of Asian black bears are relatively small, but massive, particularly in the lower jaw. Adult males have skulls measuring 311.7–328 mm (12.3–13 in) in length and 199.5–228 mm (7.9–9 in) wide, while females have skulls measuring 291.6–315 mm (11.5–12.4 in) long and 163–173 mm (6.4–6.8 in) wide. Compared to other bears of the genus Ursus, the projections of the skull are weakly developed; the sagittal crest is low and short, even in old specimens, and does not exceed more than 19–20% of the total length of the skull, unlike in brown bears, which have sagittal crests comprising up to 41% of the skull's length. Although mostly herbivorous, the jaw structure of Asian black bears is not as specialised for plant eating as that of pandas: Asian black bears have much narrower zygomatic arches, and the weight ratio of the two pterygoid muscles is also much smaller in Asian black bears. However, the lateral slips of the temporal muscles are thicker and stronger in black bears.
Asian 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: In the Ussuri territory, black bears can spend up to 15% of their time in trees. Asian 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. Asian black bears will rest for short periods in nests on trees standing fifteen feet or higher. Asian 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 steeper 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. Asian 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.