Borneo's orangutans (Pongo pygmaeus) are dying at a terrifying rate, heading towards the brink of extinction and, to paraphrase the poet, however much we believe ourselves absolved, we will be forever implicated in the disappearance of one of the most charismatic and beloved species on the planet. A new study published in the journal Current Biology has found that in just sixteen years, from 1999 to 2015, over 100,000 orangutans died in Borneo and the island's population fell drastically.

Unsustainable forest management

The main cause of the decline of these great apes is the unsustainable exploitation of natural resources in tropical areas. The effects on wildlife of the destruction of these ecosystems, which are characterised by high biodiversity, are still poorly understood. The researchers who conducted the study used field survey data, models of primate nest distribution and remote sensing to investigate the impact of resource overexploitation and land-use changes on the distribution of orangutan density. According to the researchers, between 1999 and 2015 half of the orangutan population — classified as "critically endangered" by the Iucn Red List in 2016 — fell victim to deforestation and intensive plantations.

Hunting orangutans

As well as suffering the destruction of their habitat, orangutans are frequently victims of hunters and farmers who kill them by any means available to eat their meat, capture their young to sell as pets, and protect crops. According to the researchers, between 70,000 and 100,000 orangutans currently survive in Borneo, and they predict that, without concrete conservation policies, a further 45,000 individuals will disappear over the next 35 years. The researchers identified 64 distinct orangutan groups, but only 38 of these are believed to comprise more than 100 individuals — the minimum number for a group to be considered viable.

Worse than expected

Local orangutan populations have declined by as much as 75 per cent, according to the research findings. "I expected a fairly sharp decline, but not of this magnitude," commented Serge Wich, a researcher at Liverpool John Moores University and co-author of the study. "While we were doing the analyses, we ran them over and over again to see if we had made mistakes somewhere. We thought the numbers for orangutan decline couldn't be that high, but unfortunately they are."

What can be done to save orangutans

To prevent the disappearance of these gentle primates, it is necessary to tackle the root causes through political and social initiatives. For example, better planning of land use, resource exploitation and infrastructure development is essential. It is also important to teach local communities about the value of orangutans. "We need to work with people to help them understand that orangutans are not dangerous and that it is illegal to kill them," said Wich. "It could help to find Indonesian and Malaysian ambassadors who raise awareness of the importance of orangutans through social media." Given the enormous impact of oil palm plantations on orangutans, consumers too can make a difference by choosing brands that use only sustainable palm oil.