The Asian black bear (Ursus thibetanus), also known as the Asiatic black bear, moon bear and white-chested bear, is a medium-sized bear species native to Asia that is largely adapted to an arboreal lifestyle. It lives in the Himalayas, southeastern Iran, the northern parts of the Indian subcontinent, the Korean Peninsula, China, the Russian Far East, the islands of Honshū and Shikoku in Japan, and Taiwan. It is listed as vulnerable on the IUCN Red List, and is threatened by deforestation and poaching for its body parts, which are used in traditional medicine.
Characteristics
The Asian black bear has black fur, a light brown muzzle, and a distinct whitish or creamy patch on the chest, which is sometimes V-shaped. Its ears are bell shaped, proportionately longer than those of other bears, and stick out sideways from the head. Its tail is short, around long. Adults measure at the shoulder, and in length. Adult males weigh with an average weight of about . Adult females weigh , and large ones up to .
Asian black bears are similar in general build to brown bears (Ursus arctos), but are lighter and smaller. The lips and nose are larger and more mobile than those of brown bears. The skulls of Asian black bears are relatively small, but massive, particularly in the lower jaw. Adult males have skulls measuring in length and in width, while female skulls are long and 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 specialized for plant eating as that of giant 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. The lateral slips of the temporal muscles are thicker and stronger in Asian black bears.
In contrast to polar bears, Asian black bears have powerful upper bodies for climbing trees, and relatively weak hind legs which are shorter than those in brown bears and American black bears. An Asian black bear with broken hind legs can still climb effectively. They are the most bipedal of all bears, and have been known to walk upright for over a quarter of a mile. The heel pads on the forefeet are larger than those of most other bear species. Their claws, which are primarily used for climbing and digging, are slightly longer on the fore foot (30–45 mm) than the back (18–36 mm), and are larger and more hooked than those of the American black bear.
On average, adult Asian black bears are slightly smaller than American black bears, though large males can exceed the size of several other bear species.
The famed British sportsman known as the "Old Shekarry" wrote of how an Asian black bear he shot in India probably weighed no less than based on how many people it took to lift its body. The largest Asian black bear on record allegedly weighed . Zoo-kept specimens can weigh up to . Although their senses are more acute than those of brown bears, their eyesight is poor, and their hearing range is moderate, the upper limit being 30 kHz.
Taxonomy
Ancestral and sister taxa
Biologically and morphologically, Asian black bears represent the beginning of the arboreal specializations attained by sloth bears and sun bears. Asian black bears have karyotypes 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 the 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 (Upper Pliocene to Lower Pleistocene) or a larger form of Ursus minimus, an extinct species that arose 4,000,000 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.