Abstract # 113:

Scheduled for Saturday, June 19, 2010 09:15 AM-09:25 AM: Session 19 (Mezzanine Ballroom A/B/C/D) Oral Presentation


A. A. Elder
Stony Brook University, Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook, NY 11794-4364, USA

Sleeping strategies in primates have been found to be strongly influenced by predation avoidance. Emergent trees with large, open canopies are usually preferred likely because they prevent access for terrestrial predators (snakes and felids) and allow for their early detection. This is expected to be particularly true in Asia, where large-bodied aerial predators are absent. The influence of feeding competition on sleeping tree selection, however, has not been extensively explored. Here I investigate how predation risk and interspecific resource holding potential (measured as body mass and group size) may determine sleeping tree selection in an Asian primate community. Data were collected from March 2008 through October 2009 on the sleeping trees of 5 agile gibbons (Hylobates agilis), 22 siamangs (Symphalangus syndactylus), and 20 mitered langurs (Presbytis melalophos) living sympatrically in Sumatra. Measures included absolute and relative tree height, crown diameter, and liana load. Consistent with the predation avoidance hypothesis, siamangs [N=110] and langurs [N=30] slept in emergent trees with large crowns and low liana loads. Agile gibbons [N=118], on the other hand, slept in significantly shorter, smaller-crowned trees [Mann-Whitney U: P’s<0.001] and frequently chose concealed locations within densely-foliated trees [X2(2): P<0.001]. This cryptic sleeping strategy may provide agile gibbons with an advantage in feeding competition with the larger-bodied, yet ecologically similar siamangs and with the larger groups of ecologically distinct langurs. Sponsors: ASP, Leakey, NSF.