Abstract # 5872:

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J. R. Wombolt, S. Neal, M. G. Rice and N. G. Caine
California State University San Marcos, 333 S. Twin Oaks Valley Rd., San Marcos, CA 92096-0001, USA
     Because snakes have always been important predators of primates, sensory and perceptual abilities that allow for quick detection of and response to snakes is likely to have evolved. Research suggests that the snake’s unique shape allows primates to quickly detect them, but it is not known what basic visual characteristics of the snake elicit defensive responses. In this study we examined whether pattern is a visual cue that evokes anti-predator reactions in two groups of common marmosets (n=10). Six brown clay models served as stimuli. Three models were serpentine shaped and etched with scales or other line markings. The fourth serpentine model was patternless. The other two models were triangle-shaped controls, one of which was etched with scales. Preliminary analyses with Friedman’s rank tests revealed a significant difference in looking time by shape (chi-square=14.27, df=5, p=0.01); the marmosets looked at the snake with scales the longest (M=25.71s, SD=13.51s) and the plain triangle the least (M=6.57s, SD=4.83s). There was also a trend for marmosets to continue to monitor the area more after removal of models etched with patterns than after removal of the unpatterned models (chi-square=8.65, df=5, p=0.12). Finally, the marmosets alarm-called more to the patterned serpentine models than to the triangles or plain snake (chi-square=12.98, df=5, p=0.02). These results suggest that patterns are visual cues that evoke anti-predator reactions to snakes in common marmosets.