Wildfires may cause long-term health problems for endangered orangutans

May 15, 2018, Rutgers University

Orangutans, already critically endangered due to habitat loss from logging and large-scale farming, may face another threat in the form of smoke from natural and human-caused fires, a Rutgers University-New Brunswick study finds.

The study appears in the journal Scientific Reports.

In 2015, Wendy Erb, a postdoctoral researcher in the Department of Anthropology at Rutgers, was studying male orangutans in the forests of Indonesian Borneo when fires started. She and her colleagues at the Tuanan Orangutan Research Station continued working until they had to stop and help fight the blazes, which occur annually, often due to smallholder farmers and plantations clearing forests to plant crops.

A few weeks into the fire season, Erb noticed a difference in the sound of the males' "long call," which scientists believe is used to attract females and warn other males. "I thought they sounded raggedy, a little like humans who smoke a lot," she said.

Erb decided to find out if the smoke the orangutans inhaled during the fires had affected their health. Humans who inhale smoke suffer ill effects, but she knew of no studies on the possible effects on orangutans.

Erb studied four "flanged" males, who weigh about 200 pounds and have large cheek pads. She awoke each day before dawn to collect their urine in a bag at the end of a stick she held below them. Analyzing their behavior and urine, the scientists discovered the big males traveled less, rested more and consumed more calories. They also produced more ketone bodies, molecules made by the liver from fatty acids during periods of low food intake, which was unexpected because the apes were eating more, not less. Why were they burning fat?

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