Himalayan gray langur monkeys represent one of few primates able to live in temperate or alpine habitats, and little is known about their feeding behavior. I collected behavioral and ecological data on Himalayan langurs living above 3000 m elevation at Langtang National Park, Nepal in 2000 and from 2002–2004. Methods included scan sampling, continuous focal sampling, phenological sampling, and nutritional analysis of foods. Himalayan langurs were found to be largely folivorous, but with marked seasonal changes in diet, activity patterns, and travel distance in relation to changes in food availability or consumption. In addition, the monkeys frequently engaged in extractive foraging, the exploitation of hidden foods, such as the digging of underground storage organs. Such behavior has been considered rare in the Colobinae and is the focus of one major model of primate intelligence. The classical prey model from foraging theory, as modified for patch choice, consistently underestimated langur diet breadth irrespective of whether energy or crude protein was utilized as currency. Other predictions of the model were at least qualitatively supported, and it performed best when its assumptions were more closely approximated. The social prey model, in contrast, predicts differing behavior for group versus solitary foragers while in a depleting patch with two food types. In agreement with the model, langurs were more likely to take two food types from a patch when residence times were longer, and the profitability of the first food taken (energy/time) was significantly greater in social but not solitary foragers. Contrary to the model, the rate of gain before switching to the less profitable food was not lower in increasingly competitive situations. Taken together, these results have implications for current models of primate socioecology and cognition, and for the applicability of simple mathematical models to primate feeding behavior.
|Commitee:||Lovejoy, C. Owen, Meindl, Richard S, Menzel, Charles R, Norconk, Marilyn A|
|School:||Kent State University|
|Department:||College of Arts and Sciences / School of Biomedical Sciences|
|School Location:||United States -- Ohio|
|Source:||DAI-B 78/11(E), Dissertation Abstracts International|
|Subjects:||Biology, Physical anthropology, Zoology, Psychology|
|Keywords:||Cognition, Diet, Nutrition, Optimal foraging theory, Ranging, Theoretical evolutionary ecology|
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