The orangutan is the most highly endangered species of great ape. Orangutans are threatened by deforestation, poaching, the illegal pet trade, and the isolation and fragmen tation of dwindling wild populations. Their conservation is impeded by certain aspects of their ecology (e. g., a rain forest habitat) and certain features of their life history (e. g., an eight-to twelve-year interbirth interval). Added to the U. S. Endangered Species List in 1970, the orangutan is now clearly on the road to extinction. The number of wild orangutans in Borneo and Sumatra is currently estimated to have...