A previously unknown population of rare orangutans has been discovered in the forests of Indonesian Borneo, raising hopes for the species' survival, conservationists said Monday.
Up to 5,000 endangered Bornean orangutans are believed to be living in limestone mountains in East Kalimantan province after surveyors in December found 219 orangutan "nests", Nature Conservancy scientist Erik Meijaard told AFP.
The nests, sleeping platforms made of branches and leaves suspended in the trees, indicate there could be "several hundred to several thousand" orangutans living in the 2,500 square kilometre (965 square mile) area, Meijaard said.
Nardiyono, who headed the survey team by the US-based conservation group, said the discovery will aid efforts to conserve the apes.
"We are delighted with the new discovery. We consider this an important discovery as we have identified a new area where the orangutans can be found," he said.
"We are already working with the local government as well as (the) community to turn it into a protected area for the orangutans."
The orangutans probably fled into the area in East Kutai and Berau districts after massive forest fires hit Kalimantan in 1997 and 1998, said Nardiyono.
"We saw a family of three orangutans during the trip, the mother, her baby and a male. The male orangutan was angry with us and kept breaking branches and throwing them at us," he said.
Meijaard said the orangutans found in East Kalimantan belong to a subspecies, known as Pongo pygmaeus morio, known for its darker brown-black hair.
"Compared to other species, they are able to adapt better to difficult situations. They can survive in timber forests," Meijaard said, referring to forests denuded by loggers.
"They have strong jaws and can eat bark and leaves. They have smaller brains, we always joke that they are stupid."
There are an estimated 50,000 to 60,000 orangutans left in the wild, 80 percent of which live in Indonesia and 20 percent in Malaysia, according to The Nature Conservancy.