Indonesia, Sumatra island, Bukit Lawang, Orang-outan in Sumatra In the northern part of Sumatra, Indonesia approximately, 5,000 to 6,000 orangutans live in the 9,500 km2 jungle of Gunung Leuser National Park. Bukit Lawang Sanctuary, a biosphere reserve recognized by UNESCO, is one of two remaining areas where orangutans, apes with characteristically long arms and reddish brown fur, still call home. The other is in Borneo. The word orang means human in Indonesian. We share 97% of our genetic heritage with this endangered species.