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New species of orang-utan discovered in Sumatra

Female Tapanuli orang-utan (photo: Tim Laman)Female Tapanuli orang-utan (photo: Tim Laman)A colony of orang-utans, discovered in 1997 living in a remote mountainous region of the Indonesian island of Sumatra, have now been classified as a separate species. The new species, named the Tapanuli orang-utan after its local region, is a third species of orang-utan in addition to the Bornean and Sumatran orang-utans. It is the first new great ape to be identified for almost a century. Researchers from the University of Zurich, Liverpool John Moores University and the Sumatran Orangutan Conservation Programme reported that only 800 individuals remain in an area of just 1000 square kilometres (about 400 square miles). This makes the Tapanuli one of the world's most critically endangered species of ape. With goldmining already in the area and a new hydro-electric plant planned, there are serious concerns for the colony’s survival.

Male Tapanuli orang-utan (photo: Tim Laman)Male Tapanuli orang-utan (photo: Tim Laman)Studies of the orang-utans' calls, the booming noise the male apes make to announce their presence in the forest, revealed subtle differences between the species (the Tapanuli’s is higher-pitched than the Sumatran, longer than the Bornean). The Tapanulis’ diet is also unique, including caterpillars and conifer cones. There are also minor, but consistent, differences in the shape of the Sumatran, Bornean and Tapanuli skulls (that of the Tapanuli male is smaller). Tapanulis also have more cinnamon-coloured fur than Borneans, and a frizzier texture than the Sumatrans. Tapanuli dominant males have prominent moustaches, while the females have beards—both features unique to Tapanulis. The researchers were surprised to find such a distinct population, given that Sumatran orangutans live only 100 kilometres (60 miles) away, to the north of Lake Toba.

Bornean (left), Sumatran (right) (Eric Kilby / Aiwok)Bornean (left), Sumatran (right) (Eric Kilby / Aiwok)

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