By Ian Williams
NBC News Correspondent

Refugee camps can be pretty desperate places, wherever you find them, with no shortage of agonizing stories of suffering and survival - but also of resilience and hope.

The sprawling hillside complex run by Ian Singleton near Medan on the Indonesian island of Sumatra is no different, except here the displaced aren’t people, but one of our closest living relatives – orangutans.

“These are the lucky few,” Singleton told me. “They are effectively refugees from forests that no longer exist.”

HOW TO HELP: Click here for a list of organizations working to help the orangutans

Among the 46 orangutans he now has in his care is a scrawny and bewildered two-year-old named Chocolate, the newest arrival. This orangutan toddler wrapped his arms and legs around Singleton, who lifted him carefully.

“He’s a bit thin, but otherwise quite fit and feisty,” Singleton says.

Chocolate was seized from an animal trader, who’d been trying to sell him as a pet for 8 million rupiah, which is around $800. The arrested trader claimed he’d found Chocolate alone and abandoned, though to Singleton that’s inconceivable.

He believes the mother probably was shot.

“There’s no way a mother would allow a baby to be taken from her, not while she’s still alive – never in a million years,” says Singleton. The bond between mother and child is one of the strongest in the animal kingdom, a child staying with its mom for as many as nine years.

WATCH VIDEO: 'Orangutans are dying here as we speak'

Singleton runs the Sumatra Orangutan Conservation Programme, where most arrive as toddlers, many lacking the most basic forest skills – even the confidence to climb trees. You’d have thought that came naturally to a great ape, but some youngsters will only scale the branches in the presence of a keeper, who acts as a sort of surrogate mom.

That’s not a term Singleton likes. The aim of the center is to build their skills and independence for an eventual return to the wild, though initially many are dependent on him and his staff. Tempting though it is to embrace the youngsters, it's not something Singleton encourages. Once they're healthy, he wants them to behave like orangutans again.

Chocolate, with 'Rock Center' producer Jenny Dubin.

Further up the hill I was introduced to Leuser, a big male, probably more than 40 years old and blind.

“One day he went too near farmers at the edge of the forest and they took pot shots at him. They put 62 air rifle pellets into him, mostly around the head,” Singleton says. Forty-eight are still there, and the x-ray resembles the speckled roof of a planetarium.

Leuser won’t be returning to the wild any time soon, but he has fathered twins in the rescue center.

In the top corner of a nearby cage, 9-year-old Bahroeni was sitting inside a large tire, a dangling leg encased in a cast. He too had been a sold as a pet when he was a toddler and as he grew up the nylon rope that tied him to a fence was never removed.

“It acted like a saw,” Singleton explained. “It cut grooves in his bones and severed the Achilles tendon.”

He was operated on recently by a European surgeon, who’s optimistic about a full recovery.

“These orangutans are the survivors. Most don’t get this far.”

In a nearby cage another youngster called Marvel sat nursing a darkened stump. The damage from a chain was too severe to save his foot.

“Hello mate,” Singleton said, stroking Marvel’s head. “You’re a nice little lad.”

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Bahroeni was named after the palm oil plantation from where he was rescued. The relentless march of the palm oil business is the biggest threat facing the orangutans’ dwindling habitat. Plantation owners as well as small holders frequently regard them as pests, though there is profit to be had in selling on the babies as pets, even though that’s illegal.

“The law is very clear, but the enforcement is very weak,” Singleton said, tickling one of the toddlers, who reacts with child-like convulsions.

“They completely lose all control of their arms when they are tickled.”

As we spoke, a group of keepers from the rescue center carried on a stretcher an anaesthetised young male named Dito. They lay him out on an operating table in the medical center and, after making a small insertion in his neck, they implanted a transmitter.

Singleton with a boxed up 'refugee' being transported for release in an undisturbed part of forest

Dito was ready to go back to the wild and the transmitter would help Singleton monitor his movements. “So you know what they’re doing, where they’re going. That they are okay.”

The key aim of the rescue center is to give the orangutans the confidence and independence for life in the wild. Many will have spent years chained as a pet and will have to learn to find and eat forest food and make nests. In the wild, orangutans rarely come down from the forest canopy.

When they are ready for the wild, Singleton has identified an area of remote and relatively untouched forest near the tip of north Sumatra. He’s already released 30 orangutans up there and hopes, eventually, to create a viable new community.

“The aim is to establish a new population of free living orangutans which will hopefully be sustainable in the future.”

Most of Singleton's refugees come from an area of peat forest called Tripa, which is still home – just – to the world’s densest population of wild orangutans and where he is leading a battle to save what remains of the forest – and the great apes.

For all the suffering he sees at his own “refugee camp” he is an optimist, believing the tide may be turning in favor of Indonesia’s once lonely conservationists, and that the impunity with which the plantations destroyed the forest is at last being challenged.

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And in the meantime there is nothing that can match the satisfaction of seeing returned to the wild the often bruised and terrified animals that turn up at his rescue center.

“Now they have a second chance of spending 30 or 40 years in the wild, and of having four or five babies,” he told me as, days later, we tracked some recently released orangutans.

There was a movement of red fur through the thick forest canopy above us.

“I get a real kick out of this “It’s as if they never left, and if we’d not been here they’d have died.”