Finding orangutans in the rainforests of Borneo used to be easy. When European explorers went there in the 19th century, they shot dozens of the animals. Since then, the great orange apes have declined in numbers so much that they are now critically endangered.

Research published last week by Maria Voigt and colleagues concludes that the population fell by 100,000 — about a 50 percent decline — between 1999 and 2015, thanks to deforestation and hunting. But there is still hope that the species can survive.

“People working on the ground know that the orangutan can be saved,” say the study’s authors. “It requires persistence, good collaboration with governments, strong support from local people, and help from companies that manage the land.”

So it is promising that in Sabah — one of two Malaysian states in the northern part of Borneo — the government and industry have signed a deal that will see about 30 per cent of the land dedicated as forest reserves by 2025.

To understand what kind of habitat orangutans need to survive there, Sol Milne of the University of Aberdeen and colleagues have used drones to take high-resolution photos across 260,000 hectares of rainforest, oil palm plantations and other land uses.

The aim is to find and count orangutan nests to estimate how many of the apes different habitats support. The researchers are also seeking strangler figs, the pop-up restaurants of the rainforests, whose figs are among the favourite foods of orangutans and many, many other species of wildlife.

But it is a huge task — each drone flight yields hundreds of images. That’s where you and I come in. Milne has set up an online project that anyone with a computer can join.

You can hover over the forest, zooming in and out in search of nests and strangler figs. Both are distinctive from the air. Nests appear as round brown patches in the foliage, while the strangler figs look like bald spots in the canopy from which pallid branches radiate outwards (see photo below).

It is strangely addictive, and also relaxing — a better way to spend a few spare minutes online than scanning social media. So far more than 100 people have taken part. To join in, click here and start hunting.

References

Voigt, M. et al. 2018. Global demand for natural resources eliminated more than 100,000 Bornean orangutans. Current Biology DOI: https://doi.org/10.1016/j.cub.2018.01.053

Davis, J.T. et al. 2013. It’s not just conflict that motivates killing of orangutans. PLOS One https://doi.org/10.1371/journal.pone.0075373

Meijaard, E. et al. 2010. Declining orangutan encounter rates from Wallace to the present suggest the species was once more abundant. PLOS One https://doi.org/10.1371/journal.pone.0012042

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Photo credit

Male Bornean orangutan by Eric Kilby (Wikimedia Commons)