Sumatran rhinoceros
Gunung Leuser National Park is one of the two remaining habitats for Sumatran orangutans ("Pongo abelii"). In 1971, Herman Rijksen established the Ketambe Research Station, a specially designated research area for the orangutan. Other mammals found in the park are the Sumatran elephant, Sumatran tiger, Sumatran rhinoceros, siamang, Sumatran serow, sambar deer and leopard cat.