Abstract # 3092 Event # 30:

Scheduled for Saturday, September 17, 2011 01:45 PM-02:00 PM: Session 8 (Meeting Room 408) Oral Presentation


SLEEPING SITE SELECTION IN RELATION TO THE DISTRIBUTION OF FOOD RESOURCES IN WILD GIBBONS (HYLOBATES LAR) AT KHAO YAI NATIONAL PARK, THAILAND

J. E. Berner and U. H. Reichard
Southern Illinois University, Anthropology Department, Carbondale, IL 62901, USA
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     Sleeping site selection in primates has commonly been explained through five non-exclusive hypotheses: predation avoidance, food access, parasite avoidance, comfort/thermoregulation, and range/resource defense. Among these, the assumption of optimized food access often features prominently despite little quantitative data. We tested the food access hypothesis for the selection of 59 sleeping sites in a population of white-handed gibbons (Hylobates lar) from July-November 2010. We investigated the relationship between sleeping site location and important food sources visited throughout four home ranges. Important sources were defined retrospectively as trees in which gibbons fed for longer than the average feeding duration in all sources visited that day. We found the distance traveled between the last important feeding tree and the sleeping tree was significantly shorter than the average distance traveled between all other important feeding trees that day. Also, the time spent feeding at the last source was significantly longer than the average time spent feeding in all important food sources. Throughout our study, a sleeping tree was only once reused despite repeated use of the same last important food source suggesting that reducing predation risks may be an additional factor influencing sleeping site selection. We conclude that white-handed gibbons select sleeping trees strategically to maximize access to important food trees and probably minimize energy expenditure through shorter travel distances, but that additional influences should not be neglected.