Orangutans take the logging road

In the latest stage of his field research, Brent Loken has observed that the Bornean orangutan not only regularly walks Wehea Forest floors to travel but also hits newly constructed logging roads.

The 38,000 hectare mostly undisturbed rainforest in East Kalimantan, where an international team led by Loken has been studying orangutans and clouded leopards for two and a half years, is surrounded by logging concessions.

To date Loken, a former recipient of the Trudeau Doctoral and Vanier Canada Graduate scholarships, thought that Borneo's swinging male apes only occasionally dropped down from their rainforest home's canopies to travel its floor.

Loken's latest discovery helps to reveal that orangutans may be trying to adapt to the rapid and unprecedented loss of their Borneo habitat, which is increasingly being eroded by timber plantations, agro-forestry and mines.

"These findings indicate these apes' terrestriality may be a regular strategy employed almost equally by males and females," says Loken, who co-founded the NGO Integrated Conservation (ICON), after witnessing Borneo's rapid loss of forest. "We knew that large males tended to walk the ground. However, we found that males and females, even females with babies, were recorded almost equally walking on logging roads, trails and ridges."

Researchers installed motion-triggered cameras in three regions of the Wehea Forest--one ancient and untouched, one previously logged and recovering, and one region adjacent to Wehea Forest that is now being logged. Daytime photographs of orangutan movements revealed that the apes frequently hike through pristine and regenerating forests, cleared areas, and even along deserted logging roads.

Their expanding avenues of travel may be an adaptive strategy that could improve their chances of surviving sustainable logging. But Loken cautions: "We must be careful not to reinforce the notion that orangutans can survive in any human-altered landscape. They still need trees and lots of them, and the protection of Borneo's remaining forests should continue to be of the highest priority for Indonesia and the rest of the world."