Student Prize Award Abstract
1997 Poster Paper Award

FEEDING PARTY DYNAMICS IN RESPONSE TO FOOD AVAILABILITY IN WHITE-FACED SAKIS OF LAGO DURI, VENEZUELA

A.L. Harrison and M.A. Norconk
Department of Anthropology, Kent State University, Kent, OH 44242

Primates may exhibit increased aggression when a number of individuals congregate to feed in a limited amount of space. White-faced sakis, Pithecia pithecia, maintained low levels of agonism although several individuals often feed simultaneously within the same tree crown. To understand how P. pithecia minimize aggressive interactions while feeding, data were collected on a cohesive group of six white-faced sakis, from March to May 1996. A focal-animal time-sampling technique was employed to record feeding party adjustments to changes in food abundance and tree crown volume for 123 trees. The March/April (late dry season) samples were almost entirely seeds from Licania discolor [Chrysobalanaceae] (92% of samples), while the May samples (early wet season) revealed both decreased reliance on Licania and reduced overall fruit abundance. Although the number of agonistic interactions increased as fruit abundance decreased, aggression was less dependent on crown volume than fruit abundance. Intragroup spacing remained constant irrespective of Licania crown volume (Pearson's r=-.0343, ns), but distance between individuals increased significantly as fruit abundance decreased (Pearson's r=-.1009, P<.001). These data suggest that P. pithecia mitigate aggression by adjusting feeding party size and interindividual distance according to food abundance irregardless of crown size. Support provided by Warren G. Kinzey Fund grant to E. Cunningham and NSF BNS 90-20614 to W.G. Kinzey and M.A. Norconk.