Abstract # 95:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation

Urine Washing and Sniffing in Wild White-faced Capuchins (Cebus capucinus): Testing Functional Hypotheses

F. A. Campos1, J. H. Manson2,3,4 and S. Perry2,3,4
1University of Calgary, Department of Anthropology, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada, 2Department of Anthropology, University of California, Los Angeles, USA, 3Center for Behavior, Evolution and Culture, University of California, Los Angeles, USA, 4Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
     Urine washing (UW) consists of depositing urine on the hands and/or feet. Although UW is taxonomically widespread among strepsirrhines and platyrrhines, its functional significance remains unclear. We used 2274 hr of focal follows of 35 adult and subadult wild white-faced capuchins (Cebus capucinus) to test (a) the inter-group signaling, intra-group social signaling, and thermoregulatory hypotheses for UW and (b) the hypothesis that individuals sniff each other’s urine and other traces to gather socially significant information. Males engaged in significantly more UW than females (Mann-Whitney, p < 0.004). All five alpha males engaged in more UW than subordinate males (Mann-Whitney, p < .001), including four alpha males who increased their UW rate following their rise to alpha rank. Males engaged in significantly less UW while in view of other males than at other times (Sign test, p < .001). Male-male sniffing rates were not correlated with either aggression rate or dominance rank distance. UW rates did not increase while subjects were in parts of their home range where more inter-group encounters occurred. UW rates were highest in the morning and late afternoon, presumably when temperatures were coolest. These data do not provide clear support for either the thermoregulatory or social signaling hypotheses. We suggest that additional studies in the wild and experiments with captive capuchins may be necessary to determine function of UW in this taxon.