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When authorities were called about reports of an orangutan in an Indonesian village, they arrived to find it bound with ropes by concerned local people. Worried about the animal’s proximity to humans, plans for translocation were made: removing it to an undisturbed forest habitat, far from human settlements, where it could peacefully live in the treetops. But when they finally identified the 20-year-old male, they found it had been relocated before, but, instead of settling in the new site it had travelled about 130km (80miles) away.
Researchers are starting to realise that many great apes struggle when they are moved far from their homes, despite well-intentioned efforts to protect them.
Orangutans are commonly moved by authorities in Malaysia and Indonesia if they are judged to be threatened by forest fires, damaging crops or in danger from human development. But a new study of nearly a thousand translocations in Indonesia between 2005 and 2022 has raised fears that the practice is doing more harm than good, often leaving orangutans lost, hungry and in conflict with incumbents. Many make the journey home, travelling more than 100km back to the places they grew up.
“Some of these animals are really old. In one instance, a 60-year-old male was moved. To you and me, that’s like if someone kidnaps your grandpa and knocks him out, blindfolds him, drives him miles away from his neighbourhood, and then drops him off in some city he’s never seen, where the people are unhappy to see him and might be aggressive,” says lead author Julie Sherman, the director of Wildlife Impact.
The analysis has found that nearly a third of captured orangutans make their way back to their original capture site. Mothers and their infants are sometimes separated, threatening the survival of young orangutans that spend up to nine years as a dependant, according to the study published in the journal Plos One. More than 80% of animals were healthy when captured, scientists say, raising concerns about whether many translocations were necessary in first place.
“Moving animals away and out of sight may be convenient for humans but it is taking its toll on these majestic animals,” says Serge Wich, a professor of biology at Liverpool John Moores University and an author on the study.
Orangutans are among our closest relatives in the natural world, and were once widespread across southeast Asia. The last of the great apes are now found on the islands of Borneo and Sumatra, clinging on in the remaining fragments of forest and classified as critically endangered. Amid fears of a fresh wave of palm oil plantation expansion in the region, conservationists are working out the best methods to protect the three orangutan species: Bornean, Sumatran and Tapanuli. While all have experienced dramatic declines in recent years, the Bornean is the most common, with about 105,000 remaining. There are about 14,000 Sumatran orangutans, and the Tapanuli orangutan is the most endangered great ape in the world, numbering just 800 in an isolated part of Sumatra.
The researchers reviewed news stories, government reports and scientific research to make the assessment. They warn that the policy of moving the great apes – sometimes far from their original territories – was disrupting orangutan social structures. Females typically live in small rainforest territories of about 8 sq km (3 sq miles). Males have larger territories, visiting several females, and are often solitary. When moved to unfamiliar areas, orangutans sometimes struggle to find food and are immediately in competition with unfriendly neighbours, according to the study.
More than 75% of orangutans live outside protected areas, and can exist happily between fragmented areas of forest, cropland and plantations, meaning that people sometimes stumble upon them in unexpected places. In Indonesia, the government and wildlife sanctuaries oversee the capture and movement of the animals. The Indonesian government did not respond to request for comment from the Guardian.
Wich says that more effort is required to encourage people living on forest edges to coexist with the great apes instead of moving them to unfamiliar areas.
“It is really key that we work with local communities and companies to find a solution for this. This is not a sustainable way for the future. We can’t capture all the animals that are on the edge of the forest. There’s going to be more and more forest edges, unfortunately, as development continues and roads come in. We need to find a way to keep animals where they are and manage them in a matrix of forest, oil palm and community gardens. Otherwise, we’ll end up with very small populations in bits of forests,” says Wich.
Separate modelling about the impact of translocations and killings has raised fears about the future viability of orangutans over the next 250 years. They are slow to reproduce, with females reaching sexual maturity at between 10 and 15 years, typically having babies every decade. The combination of moving adults and killing them could result in large population falls, researchers warn.
Sherman says inspiration could be drawn from an unlikely source. “We [need to] make it feasible for people and orangutans to coexist alongside each other, akin to how it is with foxes in the UK,” she says. “You could kill them all, move them all. Or, find a way to coexist with them – because they’re happy using the spaces that we are in.”
