Abstract # 6104 Event # 127:

Scheduled for Friday, June 19, 2015 10:45 AM-11:00 AM: (Cascade E) Oral Presentation


FEMALE COMPETITION IN ZOO LIVING MANDRILLS (MANDRILLUS SPHINX): EFFECTS OF DOMINANCE RANK AND REPRODUCTIVE STATE

D. R. Williams1,2 and K. E. Jaffe1,3
1Sonoma State University, Primate Ethology Research Lab, Rohnert Park, CA, USA, 2Department of Psychology, Sonoma State University, Rohnert Park, CA, 3Department of Anthropology, Sonoma State University, Rohnert Park, CA
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     It is hypothesized that female-female competition will be most intense during sexual swelling, as the potential for reproductive success is highest. Therefore, we used sexual swelling as an indicator of reproductive state to test the following predictions on a captive group of mandrills at San Francisco Zoo: (1) Dominance interactions (DI) and sexual swelling are associated; (2) The dominant female engages in more DI while fully swollen than subordinate females. We employed continuous sampling, consisting of 30 minute observations, collected between August-December 2014 (60 hrs.). Our sample of females was small (N=3) and sexual swellings were categorized: 1=no swelling, 2=some swelling, 3=fully swollen. The female dominance hierarchy consisted of the 1st dominating the 2nd ranked female, and the 2nd dominating the 3rd ranked female. DI were associated with sexual swelling (chi-squared: x2=6.143, p<0.05). 84% of the DI between the 1st and 2nd ranked females occurred when the 1st ranked female was fully swollen (goodness-of-fit: x2=37.805, p<.001). DI between the 2nd and 3rd ranked females were not associated with sexually swelling. Compared to the 2nd, the 1st ranked female engaged in more DI when fully swollen (multinomial regression: Exp(B)=46.286, p<.001). These data offer some support for the 1st ranked female engaging in more dominance interactions when fully swollen—that is, the dominant female is apparently more competitive when the potential for reproductive success is highest.