More than a thousand orang-utans are to be released back into the wild as part of a project to save the species.

The first 90 of the great apes are to be transported early next year from a rescue centre to a protected area in the heart of Borneo.

Two valleys, big enough to support 1,150 orang-utans, has been identified by conservationists as a suitable new home for the endangered animals.

Orang-utans were once common across South-East Asia but are now restricted to Borneo — where there are an estimated 35,000 to 50,000 — and Sumatra, where there are about 7,500.

Illegal logging, mining and the rapid expansion of palm oil crops have caused numbers to drop and the apes are one of the most rapidly declining species in the world.

Each year an estimated 4,000 to 5,000 orang-utans are killed or made homeless as rainforest is cleared to make room for palm oil crops.

While many of the animals are beaten or hacked to death, conservationists have been able to rescue some of the displaced creatures, mainly the young.

Conservationists from the Borneo Orang-utan Survival Foundation UK are now confident of securing sufficient funding to begin returning the rescued animals to the wild and intend to transport the first batch in January or February.

The Betikap and Sepathawung valleys have been identified as ideal homes. They supported large numbers of orang-utans before hunting all but wiped them out.

Both valleys in the Murung Raya district of central Kalimantan are now protected by law and are big enough to provide food and shelter for 1,150 orang-utans. “They’re ideal for the orang-utan and it’s been approved at every level of the Indonesian Government,” Michelle Desilets, of the survival foundation, said.

“A hundred years ago it seems there was a substantial orang-utan population there, but it has been reduced to just a few by hunters.

“We now have the support of the people in five villages in the area. They will keep an eye on the orang-utans and support them. In return, the villagers will get facilities for medical care and schooling.”

The catastrophic fall in ape numbers in Borneo is largely attributed to the palm oil industry, which is clearing land to make way for the crops. Palm oil, derived from the fruit of oil palms, is a lucrative crop and is used both in biofuel and as a cooking oil. In the past 35 years Indonesia is estimated to have lost more than 100 million acres of forest — and much of it from orang-utan territory in Borneo.

Of the 1,150 apes to be returned to the wild, 600 already have the skills to survive unaided and 550 are estimated to require rehabilitation.

Orang-utans rescued by the survival foundation are sent to a 63-hectare (155-acre) holding centre, where they are treated for injuries and illnesses before rehabilitation work begins.

Younger animals are taught how to survive in the wild without a mother, while those too badly injured to cope in the forest are cared for.

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