Pushing on 400 kilograms, baby Paichit knows when it’s feeding time.

He lets out an appreciative bellow, a rumbling baby elephant purr from his patch in the Sumatran jungle, as soon as his mahout (keeper) Julkarnaini approaches bucket in hand.

“He’s getting much healthier,” observes Julkarnaini, now using the bucket to give Paichit a bit of a bath. “At first he was very thin, but after a month here he’s putting on weight.”

Earlier this year baby Paichit, one of the critically endangered Sumatran elephants, was found stranded and starving in a palm oil plantation in Aceh, on the northern tip of Indonesia’s Sumatra island. Paichit’s father had been shot and the rest of the herd had fled in fright.

When he was discovered, Paichit was so malnourished the shape of his ribs was visible from beneath his sagging skin. On arrival at a centre run by the Aceh Natural Resources Conservation Agency (BKSDA), an intravenous drip was immediately fixed to his ear.

“Paichit was really in a bad condition when he first arrived, he was very dehydrated, he was suffering from shock, stress and he was very thin, malnourished, and his skin was in a bad way,” recalls BKSDA veterinarian, Dr Rosa Wahyuni.

And now? Paichit spends his days in his patch in the jungle, about about half a kilometre from the centre, with his devoted mahout Julkarnaini wandering up to see him half a dozen times a day to feed and bathe him and provide his favourite foods, crispy white turnips and buckets of sugar water. An assessment of his progress a month on (no elephant scales, so a long measuring tape is slipped around his growing belly and back instead) makes everyone happy. “We estimate that he has put about 80 kilograms on since he arrived,” says Wahyuni, whose veterinary practice also includes tigers, monitor lizards and crocodiles. “He has started to improve. He has a good appetite, his eating and drinking habits are good, his body weight has increased and the condition of his skin is better too. The priority health signs are all positive so far.”

Julkarnaini gives Paichit a bath. Turnips are his favourite food. Photograph: Gomos Simanjuntak

Paichit is one of a tiny subspecies of the Asian elephant, the Sumatran elephant, which has declined by a devastating 80% in 25 years. At best, there are only 2,800 left. In 2012 the classification of Sumatran elephants was changed from “endangered” to “critically endangered” and the WWF estimates the species are not likely to survive in the long term.

Poaching is an issue, but deforestation and habitat loss is the number one problem. Over the past two decades Sumatra’s rich rainforests have been decimated to make way for timber and palm oil plantations, and the natural habitat of native species such as Sumatran elephants, tigers and rhinos has been gutted. From 1985, Sumatra’s rainforest has more than halved in size – shrinking from 25m to 10.8m hectares (61.8m to 26.7m acres) in 2014.

Unsurprisingly, having lost nearly 70% of their habitat in one generation, the island’s elephants end up tramping through villages and plantations, eating the spiky oil palm fruit, unwittingly guzzling up the local community income and causing chaos and destruction. In the world’s largest palm oil producing nation about 80-90% of the human-elephant conflicts in Sumatra occur in concession areas for timber and oil palm.

“When the elephants come they destroy everything, including people’s houses, so people get angry, right. So many people see them as pests,” explains Wishnu Sukmantoro, an elephant specialist at WWF Indonesia. “There was one case for example, in 2013, when one person died. So then a week later, someone from that community found the elephant and killed it. It was a revenge killing.”

It appears this is what happened to Paichit’s father, who was shot dead in the oil palm plantation in east Aceh where baby Paichit was found. But according to his carers Paichit’s own chances of survival are looking strong. “If it was a drinking competition, he’d be a legend,” jokes New Zealander Murray Munro, or “Muzza”, as he watches Paichit down his bucket of sugar water. “He’s good with his trunk. He can rip grass out with it, so he has had enough time to learn because when they are tiny they’ve got no idea what to do with the trunk,” he says, “It’s all over the place.”

“He’s feisty, he’s got good energy, he’s a pretty relaxed young guy,” he goes on. “He doesn’t make a lot of noise, only when he’s hungry, he will certainly let you know but he’s got good strength. He is putting on weight which is fantastic and has a really good demeanour. He is quite independent, which is a good sign because the males will become solitary when they turn a certain age, they will go out of the herd they have been brought up in and they’ll have to make their own way in life.”

Munro, who works in an elephant conservation centre in Nepal, dropped everything when he heard about Paichit’s rescue and travelled to offer his support and experience, after successfully helping another orphaned baby Sumatran elephant by the name of Bona five years earlier. In that case he’d set up a crowdfunding campaign to raise the $2,000 (£1,640) each month needed to feed her, including money to pay for kilograms of “white powder”, bags of baby elephant supplements and vitamins (which raised eyebrows as they traveled through Indonesian customs). Bona is six years old and thriving now, says Munro, who plans to visit her in Bengkulu, south Sumatra, in the coming weeks.

First though, he is busy working on a similar campaign to ensure Paichit fares just as well. In comparatively better condition than Bona, Munro estimates it will cost about $700 (£573) to feed the orphaned baby elephant each month.

Meanwhile the Indonesians are also focusing on ways of dealing with the broader problem. In Aceh an elephant conservation response unit (CRU) has been running for several years, where captive elephants are trained to memorise a series of commands and then employed in the field to chase wild elephants deep into the forest, and out of harm’s way. (Baby Paichit is named after one of the trainers from Thailand, who came over to share his expertise when the programme was first established.)

To minimise elephant-human conflict the teams of elephant “rangers” and their mahouts respond to reports and sightings by the local community, and well as tracking the movements of wild elephant herds through the use of GPS collars. Across Aceh there are seven CRUs and 34 elephant rangers.

“So far it has been effective,” says Wahyuni, as one of the centre’s fully grown elephants traipses past the wooden coffee stall where she is seated, “But the number of problems has increased too, so we are fighting to protect them.”

Sumatran elephants are now critically endangered and could be extinct in the wild in less than 25 years. Photograph: WWF Indonesia/Rex

Could Paichit become an elephant ranger in the long-term? Wahyuni is not sure, but believes at the moment that releasing him back into the wild would be too perilous. For now, she and Julkarnaini are concentrating on his health and his state of mind. In the last five years two other baby elephants rescued and treated at the centre failed to make it but if he gets through this initial period, they will have to think hard about providing opportunities for him to socialise. Deeply social creatures, the emotional wellbeing of elephants is just as important as it is to humans, says Wahyuni.

Once his health is on track, the centre plans to introduce Paichit to an “auntie” elephant. For now, his mahout plays a critical role. “As an orphan the mahout becomes like a father to the elephant,” says Wahyuni. “If it comes to health problems, I can handle that, but for trauma and stress, the best person to focus on that is the mahouts because they are with them all the time. If the elephant is emotionally well, everything else will be good too. Just like a human.”

Julkarnaini smiles in agreement. He has been at the centre for 20 years, and knows as much about elephants as anyone there. Becoming a mahout was a “decision of the heart”, and as for being a father to Paichit, well the baby elephant is more like his wife, he jokes. “There is no particular way to connect,” he says. “It is kind of like fate. Do you believe you can take care of the animal? It will be like that.”

Paichit has grown healthier and calmer under his watchful care. “The way I see it, this baby elephant has to live,” he tells me as we head out to feed Paichit in the afternoon sun, “We’ve had bad experiences with baby elephants before. So in my mind, this one has to make it.”

This piece is part of a year-long series on Elephant Conservation – email us at elephant.conservation@theguardian.com