Abstract # 167:

Scheduled for Saturday, June 23, 2007 09:15 AM-09:30 AM: Session 15 (North Main Hall E) Oral Presentation

Pregnancy Coloration as a Potential Visual Threat in Rhesus Macaques (Macaca mulatta)

M. S. Gerald1,2 and C. Waitt1,3
1Cayo Santiago, Caribbean Primate Research Center, PO BOX 906, Punta Santiago, Puerto Rico 00741, USA, 2Unit of Comparative Medicine, Department of Medicine, Medical Sciences Campus, University of Puerto Rico, Medical Sciences Campus , 3Department of Zoology, Oxford University
     Bright, hormonally-induced coloration among females during gestation has been reported in both Old and New World monkeys. Evidence from lizards suggests that gestation coloration serves to reject male courtship or to prevent males from reciprocating aggression toward aggressive females. The signaling function of primate gestation coloration is unknown. For a comparative approach, we experimentally assessed whether male and female rhesus macaques (Macaca mulatta) attend to pregnancy coloration. We presented 19 adult rhesus macaques with color-manipulated digital images of female faces where pregnancy coloration was present or absent, and measured visual attention and behavioral reactions. There was a significant interaction between coloration and subject sex on gaze duration [F(1,17)=4.77, p=0.043]. Post-hoc two-tailed paired t-tests (Bonferroni adjusted probability of 0.05/2 = 0.025) revealed that males gazed significantly longer at female faces displaying pregnancy coloration versus those without [t(9)=-2.77, p=0.022]. Both sexes engaged in higher levels of appeasement behavior toward stimuli with pregnancy coloration [F(1,13)=5.42, p=0.036]. For males showing signs of anxiety during trials, they did so exclusively when exposed to faces with pregnancy coloration [t(4)=-2.95, p=0.042]. Our results demonstrate that both male and female rhesus pay attention to pregnancy coloration, and their reactions suggest that pregnancy coloration may be a visual threat. The findings underscore the similar ways that females of distantly related taxa use color displays in intra-specific communication.