Abstract # 1979 Event # 234:

Scheduled for Saturday, August 19, 2006 01:00 PM-01:15 PM: Session 23 (Regency East #2) Oral Presentation


FEMALE DISPERSAL IN PHAYRE'S LEAF MONKEYS: COMPETITION FOR GROUP MEMBERSHIP AND OPTIMAL GROUPS

A. Koenig1, E. Larney2, A. Lu2 and C. Borries1
1Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364, USA, 2Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University
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     Recent evidence seems to indicate that female dispersal is quite common amongst primates particularly prosimians, platyrrhines, colobines, and hominoids. Given that dispersal is often costly, explanations for its frequent occurrence are required. Here we report on the pattern of female dispersal in Phayre's leaf monkeys (Trachypithecus phayrei) and analyze the correlates of disappearances/ emigrations and immigrations. Data were derived from five groups at the Phu Khieo Wildlife Sanctuary, Thailand (26 cases). Most females dispersed as juveniles, but roughly 42% of the cases concerned adult females. Disappearances or emigrations usually occurred during the mating season and immigrations during the birth season. Females usually dispersed alone, but co-dispersal occurred as well. Adult females left after having lost their infant, left together with their infant, or left without their infant. Three of 4 cases in which females left their offspring behind were preceded by severe fights. Most immigrations took place into groups with multiple adult males and of average adult female group size. These results suggest that female Phayre's leaf monkeys compete over group membership particularly during the mating season. Immigrations during the birth season may indicate that allocare facilitates the integration of immigrant females. For reasons yet to be disclosed, the ideal group seems to have more than one adult male and about four adult females. Supported by ASP, Leakey Foundation, NSF (BCS-0215542) & Wenner-Gren Foundation.