Will the last great ape discovered be first to go extinct?

Seeing an orangutan in the wild is always a special moment. After studying these remarkable apes for 3 decades, I’m still in awe when I watch them gracefully, in most cases, navigate the trees. Unfortunately, the chances to continue watching individuals from one orangutan species are rapidly decreasing.

Discovery of the Tapanuli orangutan

For much of my career, there were thought to be only 2 species of orangutans: one on Sumatra and one on Borneo, which are both islands in southeast Asia. While orangutans were well-known in the north of Sumatra, their presence further south was less clear. 

It was hoped they’d still be found in several areas in the south. But after many months of survey work in the early 2000s, we could only find them in one area: the Batang Toru region where they’d been reported by Erik Meijaard in the late 1990s and of course were well-known to the local communities. In the 2000s, researchers led by Gabriella Fredriksson began studying the orangutans there in more detail, and we were in for a surprise.

Initially, we believed these orangutans were Sumatran orangutans. But as we learned more about their genetics, morphology and behaviour, it became evident they were distinct from the other 2 orangutan species. In 2017 this led to their incredible identification as an entirely new species of great ape: the Tapanuli orangutan. 

Tragically, this newest great ape species may also be the first to go extinct unless urgent action is taken. With fewer than 800 individuals remaining, the critically endangered Tapanuli orangutan faces threats from habitat loss, hunting, human-orangutan conflict killing and fragmentation of its already small population.

A population hanging by a thread

The Tapanuli orangutan population is precariously small. In 2016 we estimated there to be 767 individuals, but it’s difficult to be sure: there could be as few as 231 or as many as 1,597. However, forest loss and human-orangutan conflict over the past 8 years mean their current numbers are likely even lower now. This means that there are fewer Tapanuli orangutans than mountain gorillas.

Even within the small forest area where they live, the population is fragmented into 3 main blocks. The largest 2 are very likely no longer connected enough for orangutans to move freely between them, increasing the risk of inbreeding and loss of genetic diversity, a critical issue for their survival.

A vanishing home

Shockingly, over 95% of the Tapanuli orangutan’s original habitat has already been lost to human activities. They used to roam over a much larger area of lowland and hilly forest, but even their last refuge – the hilly Batang Toru forest – is still under threat from logging and small- and large-scale agriculture. Alarmingly, massive infrastructure projects are also being promoted in this hugely sensitive area: the Martabe gold mine and a large hydroelectric dam. These activities continue to encroach on their habitat. 

Image taken from: Meijaard E, Ni’matullah S, Dennis R, Sherman J, Onrizal , Wich SA (2021). "The historical range and drivers of decline of the Tapanuli orangutan." PLoS ONE 16(1): e0238087. Fig. 3, p. 13.

Compounding the problem, Tapanuli orangutans reproduce incredibly slowly. Females give birth only once every 7 to 9 years, so even small population losses from hunting or human-orangutan conflict can have devastating long-term effects.

Protecting the Tapanuli orangutan: what needs to be done

Halting habitat loss

Stopping deforestation is essential for the survival of the Tapanuli orangutan. This requires collaboration with local communities to address their needs without further encroaching on forested areas. Large-scale agricultural expansion, however, depends on government policy. The Indonesian government plays a crucial role in halting forest loss in the Batang Toru area. In worrying news, the government has recently announced the opening up of 20 Mha of Indonesian forest for food and energy production (particularly palm oil). 

Of course, I’m not against development in general, but some locations are so valuable and precious for the biodiversity they contain that they deserve special protection. Crucially, there must be no further expansion of the Martabe gold mine or the NSHE hydroelectric power project, which both lead to loss of Tapanuli orangutan habitat. These huge developments should never have been approved in such a sensitive area, but at the very least their impacts mustn't be spread any wider. After all, gold can be found in many more places than the Tapanuli orangutan, so why continue to expand a mine here? I realise that companies try to optimise their profits, but at what environmental costs is this acceptable?

Move the slider from right to left to see the expansion of the Martabe gold mine between August 2016 and December 2024:

Move the slider from right to left to see the expansion of the NSHE hydroelectric power project between August 2016 and September 2024:

Governments of course have a huge role to play – not just in Indonesia but all around the world – as they can implement legislation that ensures environmental sustainability practices throughout supply chains. Friends of the Earth’s call for a new UK Business, Human Rights and Environment Act, which would require UK companies to complete proper due diligence and hold them accountable if they cause harm, is therefore a welcome and important one.

Preventing hunting and conflict

Though protected by Indonesian law, Tapanuli orangutans are still killed. Engagement with local communities is vital to change perceptions of fear and ensure financial benefits from co-existence with orangutans, for example through ecotourism or direct payments for orangutan management. 

It’s now widely recognised that some of the best protectors of the rainforest are Indigenous Peoples and other local communities. A key role is to work with local people to promote sustainable economic alternatives that protect nature at the same time. Conservation efforts that, for instance, focus on supporting local communities to improve agricultural yields are underway, but they require time, resources and much stronger support for community involvement.

Reconnecting forests

Companies must take responsibility for rectifying the forest loss they’ve caused in the past (alongside stopping any further deforestation as explained above). Reforestation and collaboration with local communities can also help reconnect fragmented forest patches destroyed by massive corporate infrastructure and other human activities. Creating safe passageways through agricultural areas, as well as building corridors over roads and rivers where connectivity existed in the past, is critical to allowing orangutans to move between forest blocks. This connectivity is essential for maintaining genetic diversity and their long-term survival.

The path forward: a species master plan

To secure a future for the Tapanuli orangutan, we need a comprehensive master plan co-developed by all stakeholders: local communities, companies, NGOs, scientists, the Indonesian government and international organisations. Such a plan should clearly define roles, funding sources and actionable steps. Many other species have benefited from well-implemented conservation plans, and the Tapanuli orangutan deserves the same.

One thing is clear – we must say “no” to infrastructure megaprojects in our few remaining oases of biodiversity. This is a race against time. With the right commitment and collaboration, there’s hope that the last great ape to be identified won’t be the first to disappear.

Professor Serge Wich is a conservation biologist and a specialist in the study of orangutans. Please join Serge in opposing the gold mine.