Six of the world’s eight species of bears are listed as threatened, and one common threat is the trade in body parts such as gall bladders, which can command high prices in black markets in places like China, Japan and Thailand. The six species are the giant panda of China, the Asiatic black bear, the sloth bear on the Indian subcontinent, the Andean bear in South America, the polar bear of Arctic areas, and the sun bear of Southeast Asia.
"We estimate that sun bears have declined by at least 30 percent over the past 30 years and continue to decline at this rate," says Rob Steinmetz, a bear expert with the IUCN.
Some 10,000 sun bears are probably left, adds Dave Garshelis, co-chair of the IUCN bear specialist group.
Weighing between 90 and 130 pounds, the sun bear is hunted for its bitter, green bile, which has long been used by Chinese traditional medicine practitioners to treat eye, liver and other ailments. Bear paws are also consumed as a delicacy.
Another threat comes from loggers, who are destroying the sun bear's habitat. Thailand is the only country to have effectively banned logging and enforced laws against poaching, allowing the sun bear population to remain stable there, Garshelis says.
Ironically, experts are finding medical benefits from acid found in the gall bladders of some species such as polar and black bears. "When produced in a non-invasive and ethically acceptable way, without pushing already threatened species further towards extinction, these substances are of great value to medicine," the IUCN states.
The acid is used "to prevent the buildup of bile during pregnancy; dissolve certain kinds of gallstones; and prolong the life of patients with a specific kind of liver disease, known as primary biliary cirrhosis, giving them more time to find a liver transplant," the IUCN notes.
Sources: IUCN, CITES, TRAFFIC, WWF, WildlifeDirect; reporting by msnbc.com's Miguel Llanos