There are an estimated 4,500 to 7,500 snow leopards remaining in the wild, and more than 600 are in zoos in the United States. The biggest threats to the snow leopard's survival are loss of habitat and slaughter by man. Snow leopards are officially listed as an endangered species and commercial trade is outlawed by international treaty, but there remains a market for their beautiful furs as well as their bones (to be used in traditional Asian medicine). Another serious problem besides poaching are the snow leopards killed by herdsmen. Most of these herdsmen are extremely poor and the loss of a single animal is a significant one. Recent programs have begun which provide incentives (such as food or clothing) for these people in return for protecting rather than competing with the rare cats. Research and conservation efforts on the snow leopard are led by The International Snow Leopard Trust. Selective breeding programs have been established by the Species Survival Plan in order to maintain a solid captive population of snow leopards in the United States and to minimize the detrimental effects of inbreeding.