Wildfire smoke impacts activity and energetics of wild Bornean orangutans

W M Erb,E R Vogel,E J Barrow,S S Utami-Atmoko,A N Hofner

doi:10.1038/s41598-018-25847-1

Abstract

Indonesia’s peatlands experience frequent and intense wildfires, producing hazardous smoke with consequences for human health, yet there is a lack of research into adverse effects on wildlife. We evaluated the effects of smoke on the activity and energy balance of Bornean orangutans (Pongo pygmaeus wurmbii) in a peat swamp forest at the Tuanan Research Station, Central Kalimantan. We collected behavioural data and urine samples from four adult flanged males before, during, and after wildfires between March 2015 and January 2016. During fires, particulate matter (PM10) concentrations were hazardous. Orangutans increased rest time during and after the smoke period, and decreased travel time and distance and increased fat catabolism post-smoke. The increase in post-smoke ketones was not related to changes in caloric intake and was likely due to an increase in energy expenditure, possibly related to immune response. Results show that wildfire smoke negatively affects orangutan condition, and sustained research is needed to assess the magnitude of the threat to the long-term viability of this Critically Endangered species.

Highlights

Wildfires have occurred in Southeast Asia for millennia, but are increasingly frequent and intense, with the most extensive fires in Indonesia’s peatlands[1]
Our study provides the first evidence that wildfire smoke affects orangutan condition
Orangutans reduced their energy budgets by resting more during and after smoke, and spent less time travelling shorter distances while experiencing negative energy balance post-smoke. These changes are similar to those observed during periods of fruit scarcity, when Bornean orangutans adopt an energy-conserving strategy[12,15]

Summary

Introduction

Wildfires have occurred in Southeast Asia for millennia, but are increasingly frequent and intense, with the most extensive fires in Indonesia’s peatlands[1]. Peatland fires destroy thousands of hectares of forest annually, and release tons of carbon and other gases, contributing to global climate change, and producing hazardous air pollution[4]. The most disastrous of Indonesia’s fires occurred in 1997 and contributed the equivalent of as much as 40% of the average annual global carbon emissions from the burning of fossil fuels[3]. The widespread haze produced from these peat fires had significant impacts on human health, causing an estimated 100,300 deaths in the aftermath of the fire[6]. Most of these deaths likely occurred over the course of the first year after the fire (Loretta Mickley, personal communication). When fruit is scarce, Bornean orangutans conserve energy by decreasing their active period, travel time, and travel distance, and metabolize fat reserves to produce energy[12,13,14,15], and in disturbed habitats, travel shorter distances and spend more time resting[16,17]

Methods

Results

Conclusion