Abstract # 2624 Event # 224:

Scheduled for Monday, September 21, 2009 02:30 PM-02:40 PM: Session 24 (Shell Room) Oral Presentation


STRENGTH AND STABILITY OF DOMINANCE HIERARCHIES IN FEMALE WHITE-FACED CAPUCHINS (CEBUS CAPUCINUS) AT SANTA ROSA NATIONAL PARK, COSTA RICA

M. L. Bergstrom and L. M. Fedigan
University of Calgary, Department of Anthropology, 2500 University Dr. NW, Calgary T2N 1N4, Canada
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Dominance relationships are based on competitive interactions. Patterns of dominance vary across species according to ecological and social pressures. To clarify the nature of competitive patterns among female white-faced capuchins we examined two aspects of dominance: hierarchical strength and stability. We collected behavioral data January-May 2008 [331 focal hours; 714 contact hours] on 22 adult females from 3 habituated study groups. Hierarchies were constructed based on the direction of dyadic agonistic interactions. To determine hierarchical strength, we measured the context of dominance interactions (resource related vs. social), the latency to hierarchical detection and the directional inconsistency of aggression. To assess hierarchical stability, we calculated the proportion of undecided dyadic relationships and using long-term data, we determined changes in female group membership and the average annual rank change per female. A greater proportion of dominance interactions occurred in a foraging rather than social context, latency to detection was 21 hours/female and directional inconsistency scores for aggressive interactions were <5% -all indicating considerable hierarchical strength. No dominance relationships were undecided or heavily disputed, female group membership changed by 2 females/year (1 exit, 1 entry) and mean annual rank change per female was 0.427. There were no changes in the rank order of matrilines during the last 8 years. These results indicate stability in dominance relationships despite low-grade fluctuation in female membership and changes in alpha male residency.