Ketambe -- Ketambe, a well known center for wild orangutan research in the western sector of Gunung Leuser National Park, supported a rehabilitation project for a few years starting in 1971 under the direction of Herman Rijksen, Ans Rijksen-Graatsma, and their staff. The project was funded by the Netherlands National Appeal of the World Wildlife Faund (Aveling, 1982).

Rehabilitation at Ketambe was terminated in April, 1979 when Rijksen concluded that it was ineffective and likely threatened the park’s wild population (Aveling, 1982; Rijksen, 1982). The remaining rehabilitants were translocated to the second rehabilitation site in Gunung Leuser, Bohorok, in the eastern sector of the park. Based on his Ketambe experience with rehabilitation, Rijksen (1978) was one of several orangutan experts to develop the changed rehabilitation methods that form the basis of the Wanariset ORP program (Rijksen, 1978; MacKinnon, 1992).