Abstract # 154:

Scheduled for Friday, June 22, 2012 07:00 PM-09:00 PM: Session 22 (Gardenia) Poster Presentation


GROUP COHESION IN CAPTIVE GORILLAS (GORILLA GORILLA GORILLA) AND CHIMPANZEES (PAN TROGLODYTES) LIVING IN A NATURALISTIC ZOO EXHIBIT

M. A. Shender1, K. E. Anderson1, E. V. Lonsdorf1,2 and S. R. Ross1
1Lincoln Park Zoo, Lester E. Fisher Center for the Study and Conservation of Apes, 2001 N. Clark St., Chicago, IL 60614, USA, 2Franklin and Marshall College, Lancaster, PA 17603
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     Measuring group cohesion in gregarious primate species is of interest to those studying social structure and the potential proximate and ultimate factors by which it may be affected. Existing studies of free-ranging apes use both behavioral measures of sociality and categorical classes of proximity to understand the influence of factors such as sex and dominance rank on social structure. Relatively few studies, though, have attempted to characterize the social structure of captive apes using precise measurements scaled to their enclosure. In this study, we examined social spacing of gorillas (n=11) and chimpanzees (n=6) living in naturalistic, indoor-outdoor zoo exhibits. 584 hours of data were collected over a 3-month period (May-July 2011) using 30-minute group scans on an electronic map interface. Our primary dependent measure was mean inter-individual distance (IID) in which the average distance between a subject and its groupmates was calculated for each session. An ANOVA revealed no significant effect of species [F(1,13)=2.451, P=0.141] or sex [F(1,13)=0.656, P=0.433]. However, a significant sex by species interaction effect [F(1,13)=12.506, P=0.004] was evident in which male gorillas demonstrated lower IID than females (M=7.7m, F=8.5m) but male chimpanzees demonstrated higher IID than their female groupmates (M=9.2m, F=7.9m). These results demonstrate the efficacy of a precise measure of social spacing that is possible in controlled environments and are suggestive of differential social management strategies required for these ape species.