Sumatran Orangutan
Pongo abelii Lesson, 1827
CR A2bcd

Although fossil orangutan remains are known from mainland Asia, today these threatened red apes are restricted to the islands of Borneo and Sumatra. The orangutan was once considered to represent a single species, but notable differences in appearance, skeletal structure and genetics between Bornean and Sumatran animals now lead scientists to believe that each island harbors a distinct species. On Sumatra, Pongo abelii is known only from three of the northern provinces – Aceh, Sumatra Utara and Sumatra Barat – and is roughly divided into two population units. Loss and fragmentation of tropical forest habitat are the principal threats to orangutans throughout their range, but illegal hunting for food or sport, or to obtain infants for pets, also contribute to their decline. Recently, fire and droughts have also become serious dangers on Sumatra, though not yet as severe as on Borneo. Several thousand orangutans continue to survive in northern Sumatra where they are officially protected in Gunung Leuser National Park and the Sekundur and Singkil Barat Reserves. However, illegal logging within protected areas is rapidly increasing and is the cause of grave concern regarding this species’ future.