Date of Award


Degree Name

Master of Arts



First Advisor

Reichard, Ulrich


Despite the lack of sufficient quantitative data on factors defining sleeping site choices, predation avoidance is often regarded superior over food access, avoiding parasites, comfort, and range/resource defense. With a comparative approach, all hypotheses were tested for the selection of sleeping sites in four wild white-handed gibbon groups (Hylobates lar) at Khao Yai National Park, Thailand. From July-November 2010, I recorded 59 sleeping trees for 10 adults. By consuming a large amount of food at their last important food source and sleeping nearby, gibbons maximized their access to food. Additional factors such as predation avoidance and comfort also influenced sleeping site selection. Using a multi-functional approach, I conclude that gibbons choose sleeping trees strategically to primarily maximize access to important food trees and avoid predators while factors like comfort may also influence where gibbons spend the night.




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