Over 100,000 orangutans have been killed in Borneo over the past 16 years.
The critically endangered animals died primarily due to deforestation driven by logging, oil palm, mining and paper mills.
However, large numbers of the orangutans have also “disappeared” from areas that remain forested, leading researchers to believe that they are being slaughtered.
Scientists have called the sheer number of dead orangutans “mind-boggling.”
A study published in the journal, Current Biology, showed that the rate of orangutan decline is now larger than ever, despite the population being bigger than previously thought.

According to the BBC, researchers think that the orangutans could be targetted by hunters as a retaliation against the raiding of crops.
Professor Serge Wich said that although the apes may be eating crops, they are not dangerous.
He said:
“When these animals come into conflict with people on the edge of a plantation, they are always on the losing end. People will kill them.
“Just last week, we had a report of an orangutan that had 130 pellets in its body, after being shot at in Borneo.
“It’s shocking and it’s unnecessary. Orangutans might eat farmers’ fruit, but they are not dangerous.”

Researchers are calling on Malaysian and Indonesian leaders to address the number of hunters killing orangutans.
The study also found that the apes living in Borneo are more resilient and tend to walk on the ground more than other orangutans.