Wildfire Smoke Alters Wildlife Behavior and Biophony in Bornean Forests
NASA Earth Observatory images by Joshua Stevens
Borneo's forests burn annually, producing toxic smoke that can cover a large region. The resulting air pollution, especially particulate matter, has major health consequences for humans, but little is known about how this haze affects wildlife behavior and biophony (sounds produced by animals). My Indonesian partners and I have collected soundscape recordings since 2018 in the Rungan landscape, one of the largest lowland forests in Borneo with no formal protection. This region experienced El Niño-driven wildfires in 2019 and 2023 that blanketed these forests in thick smoke. Our collaborative team is studying Rungan forest soundscapes - with a focus on a range of threatened primates, birds, herpetofauna, and insects - to understand the consequences of prolonged and repeated exposure to hazardous smoke for a range of wildlife populations.
Social-Ecological Impacts of Indonesia's Capital City Relocation
Indonesia is relocating its capital city from Jakarta to Borneo to reduce its vulnerability to climate change, more fairly distribute political power, and contribute to a green growth vision. The resulting migration and urbanization will have rapid, wide-ranging effects on the surrounding landscape that calls for radical, interdisciplinary investigation with local and international partners. With community partners, our team of natural and social scientists (Shorna Allred, Walker DePuy, Chandra Boer, Rustam, and Emi Purwanti) is working to capture perceptions about the new capital's impact, map biodiversity across the city location, monitor social-ecological change, and identify spaces of human-environment concern. We have launched co-created monitoring protocols to identify spaces and species for longitudinal research and will later meet with state and civil stakeholders to share these results. We wrote about this work for Cornell's Southeast Asia Program Bulletin.
Bioacoustic Monitoring of Endangered Apes
The biologically rich tropical forests of Borneo are experiencing rapid and extensive degradation from industrial activities. Despite housing an incredibly diverse fauna, including large populations of endangered orangutans and gibbons, the Rungan landscape is one of the largest lowland forests in Borneo with no formal protection. As most of this area is designated for conversion to plantation or as timber concessions, significant conservation challenges are to develop cost-effective methods to monitor ecological responses to anthropogenic change. With international collaborators, Frank van Veen, Mark Harrison, and Siti Maimunah and Mariaty Ayudia Niun at Universitas Muhammadiyah Palangkaraya, we have established a long-term research program to understand how environmental variation affects different species. We are conducting multidisciplinary research to evaluate the spatio-temporal distribution of flagship orangutans and gibbons in the landscape. This project seeks to highlight the conservation and scientific value of the Rungan landscape, aiding efforts to secure local support to protect its endangered biodiversity.
Wildfire Smoke Affects Orangutans
Indonesia’s peatland forests burn every year, producing toxic smoke that can cover a large region. The resulting air pollution has major health consequences for humans, but little is known about how this haze affects wildlife. Together with the Tuanan research team, I collected behavioral data and urine samples from wild orangutans to measure their short- and long-term responses to Indonesia's 2015 El Niño-driven wildfires. In the months following the fires, despite making energy-conserving changes to their behavioral patterns, orangutans were burning fat to meet their energy needs. This work is published in Scientific Reports and has been covered in Discover Magazine, National Geographic, and public radio. We recently published work documenting changes in orangutan long calling behavior and vocal quality. I wrote about our research for the Cornell Chronicle and The Conversation and was featured in a Scientific American podcast episode. This research highlights the health consequences of prolonged and repeated exposure to hazardous smoke for both humans and wildlife, and identifies an additional conservation threat to already Critically Endangered orangutan populations.
I conducted 3 years of field work as a postdoc with Erin Vogel, studying nutrition, energy balance, endocrine and immune function, behavior, and acoustics of Bornean orangutans. My project examines whether male vocal displays (long calls) honestly signal callers' health and energy status. I conducted this work while working as Project Manager of an international team promoting biodiversity and conservation of peat swamp forests.
My collaborators (Leila Porter and Anthony Di Fiore) and I conducted a year-long study of the proximate and ultimate factors influencing cooperation in wild Weddell’s saddleback tamarins in northern Bolivia from 2013 to 2014. We collected behavioral, morphological, and genetic data from individuals in 4 groups and – using genetic and observational data – are deriving pedigree relationships for the study groups. These data will allow us to 1) test adaptive hypotheses for the evolution of cooperative behaviors and 2) examine the proximate factors influencing individual participation. Click here to read press about this project. We have published a review on callitrichine infant care in Evolutionary Anthropology and a research article investigating the contributions of different group members to infant care in the American Journal of Primatology. Genetic analyses are underway, so stay posted for results!
Simakobu Loud Calls as Costly Signals
Adult male simakobu (Ali) loud-calling
Male acoustic signals may play an important role in sexual selection. If these displays are costly to produce, they may convey honest information about the caller’s competitive ability. I studied variation in calling effort of adult male simakobu. I combined behavioral observations and ecological measures with acoustic analysis to determine the influence of energy status on loud calling behavior. I assessed how call output varied in relation to physical, ecological, behavioral, and physiological measures of energy availability. This work was conducted in collaboration with Nurul Lestari, Thomas Ziegler, and Kurt Hammerschmidt, and is published in theAmerican Journal of Physical Anthropology.
Simakobu Demography & Human Disturbance
Subadult male simakobu sitting atop a roof at Camp Pungut
Among the leaf-eating monkeys of Asia, most species are polygynous, forming one-male multi-female groups. Simakobu appear to be unusual because mostly adult male-female pairs have been observed. However, the larger body and canine size of males compared to females make it unlikely that they are monogamous. At my study site, I found the typical Asian colobine pattern of one-male groups with multiple females. I compiled data from additional populations to assess the impact of hunting and habitat disturbance on simakobu demography. I found that hunting reduced the number of adult females and immatures in groups. This research highlights the need for conservation action to reduce hunting on this critically endangered species. This work was completed in collaboration with Carola Borries, Nurul Lestari, and Thomas Ziegler, and is published in theAmerican Journal of Primatology.
Acoustic Features of Simakobu Loud Calls
Adult male simakobu (Hulk)
Primate loud calls have the potential to encode information about the identity, arousal, age, or physical condition of the caller, even at long distances. While my previous research indicated that there are significant individual differences in calling rates and call durations, it was unknown what these differences may signal (e.g., age, stamina, physical condition) and which other acoustic features vary among individuals. I studied the structure and usage of calls and examined acoustic features that vary within and between individuals. Overall, I found that calls were individually distinct and may provide information about the age, stamina and arousal of the calling male, and could thus be a way for males and females to assess competitors and mates from long distances. This work was conducted in collaboration with Kurt Hammerschmidt and Keith Hodges at the DPZ, and our paper has been published in PLoS ONE.
Simakobu Reproductive Seasonality
Newborn infant simakobu (Sammy) abandoned by his mother
The forests of Southeast Asia are characterized by unpredictable periods of very high fruit availability, a phenomenon known as masting. For most primates in these habitats, reproduction occurs year-round, with more conceptions occurring during periods of high food abundance. Simakobu, in contrast, were reported to exhibit strict birth seasonality, with births limited to just 2 months of the year; however, data were very limited and it was unclear whether past observations were characteristic of the species and the what factors influence the timing of reproduction in this species. To address these questions, I assessed the seasonality of the environment and reproduction via annual patterns of rainfall, temperature, food availability, fruit-feeding, conceptions, and births. This work was conducted in collaboration with Carola Borries, Nurul Lestari, and Keith Hodges, and is published in the International Journal of Primatology.