The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


Coping with a challenging environment: nutritional balancing, health, and energetics in wild Bornean orangutans

ERIN R. VOGEL1, JESSICA M. ROTHMAN2, ALYSSE M. MOLDAWER1, TIMOTHY D. BRANSFORD1, MELISSA E. EMERY-THOMPSON3, MARIA A. VAN NOORDWIJK4, SRI SUCI UTAMI ATMOKO5, BROOKE E. CROWLEY6, CHERYL D. KNOTT7, WENDY M. ERB1 and DAVID RAUBENHEIMER8.

1Department of Anthropology, Rutgers, The State University of New Jersey, 2Department of Anthropology, Hunter College and NYCEP, 3Department of Anthropology, University of New Mexico, 4Anthropologisches Institut und Museum, Universität Zürich, 5Faculty of Biology, Universitas Nasional Jakarta, Indonesia, 6Department of Anthropology, Department of Geology, University of Cincinnati, 7Department of Anthropology, Boston University, 8Charles Perkins Centre and School of Biological Sciences and Faculty of Veterinary Sciences, University of Sydney

March 26, 2015 10:45, Grand Ballroom D Add to calendar

The peatland forests of Borneo are characterized by overall low and unpredictable fruit production. Previous work at the Tuanan Orangutan Research Station (TORP) in Central Kalimantan has demonstrated that orangutans prefer fruit and fallback on low energy foods during episodes of fruit scarcity. However, we have little understanding of how they balance and prioritize nutrients in relation to fruit availability, and how macronutrient intake influences orangutan physiology. Because orangutans are frugivores, we hypothesized they would more tightly maintain their target intake of protein (P) than non-protein energy (nPe) when ecologically constrained to eat an imbalanced diet (“protein prioritization”). We used right-angle mixture triangles to examine the relationships among physiological indicators of energetic status, health, and macronutrient intake during episodes of fruit scarcity. Data were compiled from 2,233 full-day focal follows on 49 habituated orangutans (Pongo pygmaeus wurmbii) totaling over 39,000 hours of observations. We found a negative relationship between fruit availability and the P:nPe ratio (p<0.05), and P intake was maintained more tightly than non-protein intake, a pattern that is consistent with protein prioritization. Orangutans at Tuanan frequently fell into a negative energy balance state, as evidenced by urinary ketone production, and lower levels of C-peptides, particularly when nPe intake was low. However, orangutans maintained a stable nitrogen balance state, as evidenced by urea concentration, δ15N values, and 3-MH. Preliminary analyses suggest that the link between immune function, as quantified by cytokine concentration, and caloric intake is complex and requires further examination.

Supported by USAID (Cooperative Agreement No. AID-497-A-13-00005), Rutgers University, and Universität Zürich