"If the civil war hadn't happened and they all operate and clear the forest, we'll be dealing with a few hundred orangutans now," said Ian Singleton, scientific director of the Sumatran Orangutan Conservation Programme.

"And if they clear these extra bits of forests here in the near future, then the same thing will happen again. All the orangutan will die. They don't sort of like pack their bags and move somewhere else. They stay and die," he told Reuters in North Sumatra's provincial capital, Medan.

The war in Aceh in on the tip of Sumatra had prevented logging concessions and palm oil estates, which had been granted permits during the 1990s, from operating around the so-called Leuser Ecosystem -- the last place on Earth where orangutans, tigers, rhinos, leopards and elephants can be found in one area.

The 2.6-million hectare (6.5 million acres) Leuser Ecosystem, roughly the size of Belgium and the largest protected rainforest area in Southeast Asia, covers parts of Aceh and adjacent North Sumatra province.

"By preventing them from operating has given us a second chance to save the orangutan. We may have lost around 5,000 orangutans between 1995 and 2000, and then that suddenly stabilised because of the civil war," said Singleton.

There are about 7,300 Sumatran orangutans left in the wild. The number has been relatively steady in recent years but is half as many as the early 1990s, when there were estimated to be about 15,000.

HABITAT LOSS, MORATORIUM

"In the early-to-late 1990s, there was a lot of habitat loss, especially in Aceh in the lowlands. Much of that was legal forest clearance. There was also illegal forest clearance in protected areas and there was also conversion of forest to palm oil estates," said Singleton.

The conflict in Aceh ended in 2005 with a peace pact between Jakarta and the separatist Free Aceh Movement (GAM) after at least 15,000 people, most of them civilians, had been killed in the war that lasted for nearly three decades.

Singleton said Aceh's newly elected governor, Irwandi Yusuf, was under pressure from the central Jakarta government to open at least some of the logging concessions.

In general, the Sumatra orangutan fared better than their cousins in the neighbouring island of Borneo, where annual forest fires, land clearing by farmers and plantations and poaching has drastically cut the numbers of the orange-haired apes.

"The pet trade, the captive orangutans, tend to be a byproduct of habitat loss. And because there is so much habitat loss in Borneo now, the numbers that are coming into captivity are huge. Thousands every year, and that's just lucky survivors."

The Sumatran Orangutan Conservation Programme was set up in 1990s to help save the animals by creating quarantine centres for confiscated pet apes.