Abstract # 2669 Event # 120:

Scheduled for Sunday, September 20, 2009 04:50 PM-05:10 PM: Session 11 (Mission Bay Ballroom AB) Symposium


THE FUNCTION OF FOOD-ASSOCIATED CALLS IN WHITE-FACED CAPUCHINS (CEBUS CAPUCINUS) AT LOMAS BARBUDAL, COSTA RICA DIFFERS FOR SIGNALERS AND RECIPIENTS

J. Gros-Louis1,2
1Department of Psychology, University of Iowa, E11 Seashore Hall, Iowa City, IA 52242, USA, 2Delta Center, University of Iowa
line
     

The function of vocalizations is inferred by observing recipients’ responses to call playbacks. A combination of naturalistic and experimental studies in two groups of white-faced capuchins indicates that interpretation of function differs from signalers’ and recipients’ perspectives. In playback experiments, listeners looked longer when they heard food-associated calls compared to controls [Wilcoxon signed ranks test: female vocalizer, p<0.004; male vocalizer: Rambo’s group, p<0.07; Abby’s group, p<0.04]. Females were more likely to approach the speaker after hearing males’, but not females’, food calls compared to controls [Fisher's exact test: female-female, p>0.10; male-female, p<0.05]. However, focal observations revealed that the presence of foraging individuals was a significant predictor of call rate [Random effects linear regression, p<0.00001]. Furthermore, food placement experiments revealed food quantity did not influence call production as would be expected if calls function to inform [Logistic regression, GEE estimation, p>0.7]; rather, calls served a spacing and possession function. Signalers were less likely to be approached if they called upon discovering food [Wilcoxon signed ranks test, p<0.063]. If approached, individuals who called received less aggression [Fisher's exact test, p=0.05]. These results were mirrored in focal observations [Fisher exact test, p=0.003]. Results suggest that researchers should examine proximate influences on call production and consequences of calling for the signaler when considering call function.