Orangutans are slow to reproduce and need vast tracts of contiguous forest for their long-term survival. With forest cover diminishing and orangutans being killed as agricultural pests, hunted for trade in pets, and killed for consumption, their numbers are rapidly dwindling.
The orangutans of the Batang Toru forest were only ‘discovered’ by scientists in the late 1990s and recent research has uncovered that they are genetically, morphologically and ecologically distinct from orangutans in the Leuser Ecosystem in the north of Sumatra and Aceh, and interestingly more closely related to the Bornean orangutans! The Batang Toru population is estimated at around 800 individuals and their population is already seriously fragmented. They are at serious risk of extinction if hunting and further deforestation cannot be halted.
Living in this high altitude habitat (900-1100 m asl), the orangutans of Batang Toru consume a variety of different food species never seen before in the diet of this great ape. In addition, tool use, so far only found in high-density orangutan populations in lowland swamp forest, has also been found to occur in Batang Toru.