Homeless, semi-paralysed and blind in one eye, Montana faces an uncertain future. Even if his friends find somewhere for him to live, the 15-year-old has been seriously weakened by years in assisted care.
The lethal dangers of readjustment in his natural home include men like those who shot him out of a tree when he was just a baby and the hostile attentions of his stronger neighbours. But for the source of the greatest threat to Montana's existence, say his supporters, look no further than your food cupboard.
The orang-utan, one of our closest animal relatives and the largest tree-living mammal on the planet, is in deep crisis. A once-mighty orange army of 300,000 that swung through the dense forests of much of south-east Asia has dwindled to fewer than 25,000 concentrated on the two Indonesian islands of Borneo and Sumatra, conservationists say. There, they cling precariously to life on government-protected nature reserves that are under siege by developers of one of the world's most lucrative commodities: palm oil.
Illegal logging, fires and clearances have decimated the tropical rainforest that is the exclusive home of the primates, who nest high above the forest floor. The casualties join Montana at a care centre near Pangkalan Bun in central Borneo, crowded with more than 320 homeless, orphaned and sick or injured orang-utans – a number that grows by a barely manageable 20 per cent a year, say the workers there.
Montana peers unhappily from his cage. Unlike 250 of his predecessors, who have been relocated to the jungle upriver from here since this centre was set up in 1998, he is unlikely to ever leave. "We just can't find homes for all of them," says Birute Galdikas, the famed anthropologist who runs the care facility, after producing a long list of daily needs that includes nappies for the three dozen or so babies. "We are looking at the extinction of orang-utans in the wild." She estimates that without action, the orang-utans – one of the four great apes along with gorillas, chimpanzees and bonobos, have just 10 to 15 years left in the wild.
The Borneo orang-utan is listed as "highly endangered" by the International Union for the Conservation of Nature and Natural Resources, one short step on the ladder of extinction above its Sumatran cousin, which is critically endangered. "When it goes extinct, it will be a terrible loss," says Dr Galdikas. "I can't tell you how urgent it is."
To grasp just how urgent, you have to travel from Pangkalan Bun up the chocolate-coloured Sekonyer river to the heart of one of the world's last great wildernesses, the Tanjung Putting Park, a 410,000-hectare nature reserve that is home to perhaps 6,000 orang-utans (nobody knows for sure) along with proboscis monkeys, gibbons, macaques and crocodiles.
The reserve is an oasis in a landscape pressured by human demands and the growing local population. Behind the thick canopy of mangroves and Pandanus along the Sekonyer, bald patches of cleared jungle can be seen from the boat. Guards posted along the river patrol for illegal logging and poaching.
Some orang-utans are kept as pets or smuggled out of the country and sold to perform in Thai kick-boxing matches or in circuses. But the "real issue", say scientists, is palm oil plantations.
Julia Roberts and Joanna Lumley made this journey a few years ago, with documentary crews to film one of the only places in the world where orang-utans can still be seen in the wild. Lumley is said to have been "horrified" to discover that her handbag was stuffed with cosmetics containing palm oil.
Extracted from the fast-growing oil palm tree, it is now probably the world's most popular vegetable oil, surpassing its soybean alternative and used in a tenth of supermarket products, including crisps, biscuits, toothpaste, margarines and make-up.
So ubiquitous is the oil that few UK supermarkets have ever seriously considered removing it from their shelves – and 85 per cent of it comes from Malaysia and Indonesia, the world's number one and number two producers. Often it comes from giant mono-crop plantations hewn from the tropical forests and run by agri-business concerns with powerful political support.
"Greed drives the industry," says Dr Galdikas. "The industry is tied with the political elite who are making bundles of money off this. You have to see these mansions in Jakarta to understand the money that is coming from it." She calls the clearance of central Borneo to make way for the crops a "scorched earth" policy. "It is unbelievable," she says.
Conservationists say many of the devastating fires in 1997-98 that robbed the orang-utans of perhaps 30 per cent of their habitat in Borneo and helped blanket much of south-east Asia in a dense smog were caused by forest-clearing for palm oil plantations. Those fires briefly drew attention to the plight of the Borneo and Sumatra orang-utan, but Indonesia is still converting land at a rate of at least 1,000 sq miles a year and has announced plans to raze an area half the size of the Netherlands to make the world's biggest palm oil plantation, according to the UK-based Orang-utan Foundation.
A couple of years ago, say local forest guides here, 2km was shaved off the northern end of the Tanjung Putting reserve. "Nothing is safe," says one, who explains that the valuable forest hardwood, including teak and mahogany is often sold to finance the plantations.
The reserve is dotted with elevated feeding stations, where the guides leave ripened bananas and milk to supplement the animals' diets. As a small group of tourists wait in the sweltering tropical heat, the animals descend from the forest roof in ones and twos, first mothers hugging their children, accompanied by the sound of creaking and breaking branches.
With their bulk and powerful grip, the orang-utans do considerable damage to the trees, but they also help spread the seeds for new growth in the dung they leave across the forest, a process of regeneration that has gone on for millennia.
Then the dominant male arrives, a huge 250lb bruiser named Tom by the guides, who has earned his title by beating off all the other young pretenders.
As Tom peels and eats bananas, the guide tells us he is 24 and, like all male orang-utans, lives alone. "But we don't know where, somewhere high in the trees," he says. As the forest shrinks around him, so do his sources of food, but the guides say they must not destroy the orang-utans' ability to forage, and turn them into vermin dependent on human charity. "The only way for them to survive is for us to preserve their habitat."
The destruction of the rainforest here would also deprive many other animals of their home, including some possibly not yet discovered. One estimate is that Indonesia is home to perhaps as many as 140 species threatened with extinction in the next few decades, including the Sumatran tiger and the Asian rhinoceros. And in a bitterly ironic twist, they may go the way of the dodo to meet demand for cleaner energy sources in a world choking on fossil fuels: many countries are looking to palm oil as a source of bio-fuel.
Cheap and carbon neutral, palm-oil diesel was until recently hailed as a safe, renewable alternative to petroleum, but such claims have been undermined by a series of studies. One, by Wageningen University in Holland, published this year, found the carbon released from peat swamps in Indonesia and Malaysia – drained and burned to allow plantations of palm oil trees – released 2 billion tonnes of carbon dioxide a year into the atmosphere, or 8 per cent of the world's fossil fuel emissions.
"It is like kicking your head to get rid of a headache," says Dr Galdikas. "The palm oil prices are going through the roof because of their use as bio-fuel and this, one of the poorest countries in the world, is cutting down its trees to supply the market."
Scientists say that the global warming caused by the release of this carbon is drying the forest floor, making it easier to burn and adding to the devastation.
To that double whammy – releasing vast quantities of carbon into the air while destroying the forests that suck it up – add another: the permanent, irreversible loss of countless animals. But demand for palm oil continues to rise. A $48m (£24m) palm-oil bio-diesel plant opened in Australia's Northern Territories last year and three 50 megawatt power stations are currently planned in Holland.
The staff at the Pangkalan Bun centre say each of those decisions brings the orang-utan one step closer to extinction. Senior administrator Mrs Waliyati fears more for her youngest charge, nine-month-old orphan Britney, than her oldest. "It might be too late for Montana, but what about the young ones?" she asks. The solution, she says, is as simple as it is enormously difficult. "Don't use palm oil. If you do, it means you are agreeing to cutting down the rain forest. If you don't stop, in 15 years, or sooner, there will be no place for these animals."
One of our closest ancestors
One of our closest ancestors, with 97 per cent of its DNA the same as that of humans, the gentle orang-utan was once found across Indonesia and as far north as China, but is now on the edge of extinction. Earthwatch estimates they may have as little as 12 years left in the wild, after which our only chance to see them will be in zoos, where about 1,000 are kept in captivity around the world. Their name comes from the Borneo words orang hutan, meaning "people of the forest".
Almost totally dependent on trees, the animals survive on a mostly fruit-based diet supplemented by bark, flowers, leaves and insects. They usually live and forage alone, except when mothers are nurturing their children and teaching them how to survive in the dense forests, a process that takes up to six years. Scientists believe the animals are equipped with large memories to help them locate the thousands of food sources on which they depend.
Extremely slow to breed, the inter-birth cycle in orang-utans takes up to eight years, limiting females to three or four offspring during their 45-year life span. Although successfully bred in captivity in Australia and other parts of the world, the long-term impact of captivity on the species is not known, but is likely to be negative. Scientists say it is better to save them now.
"Concern for orang-utans indicates concern for the planet," says the conservationist Birute Galdikas.