Abstract # 102:

Scheduled for Sunday, September 20, 2009 09:45 AM-09:55 AM: Session 9 (Del Mar Room) Oral Presentation


OBSERVATIONS ON A GROUP OF WILD VERVET MONKEYS (CERCOPITHECUS AETHIOPS) AFTER A PREDATOR-INDUCED GROUP FUSION EVENT IN LAIKIPIA, KENYA

K. E. Jaffe1 and L. A. Isbell2
1Sonoma State University, Department of Anthropology and Linguistics, 1801 E. Cotati Avenue, Rohnert Park, CA 94928, USA, 2University of California, Davis
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     Socioecological theory suggests that group fusion in female-philopatric primate species is rare because females experience increased costs by associating with non-relatives. We describe changes in ranging and social behavior of two groups of vervets (Cercopithecus aethiops) after group fusion induced by rapid population decline from apparent leopard (Panthera pardus) predation. Before fusion, both groups traveled significantly farther into their own territories (large group: own territory: mean=330.8 m [range: 54-980 m] vs. small group’s territory: mean=63.0 m [range: 2-212 m] [Mann-Whiney U-test: U=22.0, z=2.55, p<0.006]; small group: own territory: mean=224.1 m [range: 54-328 m] vs. large group’s territory mean=62.0 m [range: 41-76 m] [Mann-Whitney U-test: U=8.0, z=2.76, p=0.003]), suggesting that the groups were actively avoiding one another before the fusion. After fusion, the fused group traveled equally far into both territories (large group’s former territory: 143.8 m [range: 6.4-340.7 m] vs. small group’s former territory: 168.7 m [range: 25.9-295.4 m]; Mann-Whitney U-test: U=13.0; z=0.27; p=0.4). Ten days after the fusion, three females (formerly of the large group) attacked and wounded an adult female (formerly of the small group) and her dependent offspring. Severe female-female aggression has not been previously observed in vervets, even during nine other group fusion events at another site, and may have been related to the mother’s ability to keep her offspring away from the other females.