Abstract # 4228 Event # 10:

Scheduled for Thursday, June 21, 2012 02:30 PM-02:45 PM: Session 3 (Magnolia) Oral Presentation


VARIABLE PARTICIPATION IN INTERGROUP AGGRESSION BY FEMALE TUFTED CAPUCHIN MONKEYS (CEBUS APELLA NIGRITUS)

C. Scarry1,2
1Stony Brook University, Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook, NY 11794-4364, USA, 2Centro de Investigaciones del Bosque Atlántico (CeIBA), Puerto Iguazú, Argentina
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     In many primates, female participation in intergroup aggression is limited, even if between-group contest competition for food is strong. The potential costs of sexual coercion and infanticide by extragroup males are argued to promote such free-riding by females. To investigate the predictors of female participation in aggressive intergroup encounters, I followed four habituated groups of tufted capuchin monkeys (Cebus apella nigritus) in Iguazú National Park, Argentina (24 months), recording individual behavior ad libitum during encounters (n=88). Using generalized linear mixed modeling, I examined the factors influencing whether females participated in or led intergroup aggression. Although females were less likely to behave aggressively during intergroup encounters than males (p<0.001), female participation in aggressive chases or displays occurred in more than 65% of encounters. Neither dominance rank nor the presence of matrilineal kin influenced female participation. Instead females appeared to adjust their behavior in accordance with the relative competitive ability of the group (p=0.001), being more likely to participate during encounters in which their group had relatively more males. Females were more likely to lead intergroup aggression, however, when their group was at a competitive disadvantage (p=0.02), especially if they had a vulnerable infant (p=0.036). The more active nature of participation by females with infants suggests that energetic costs rather than risks from intersexual aggression determine female behavior. Supported by NSF, NGS, Leakey Foundation and Wenner-Gren Foundation.