Sunday, December 16, 2012

Capuchin monkeys learn to respond or not respond to snakes

Photo credit: Steven G. Johnson
Primates have evolved antipredator behaviors for many potential predators including snakes, crocodiles, caimans, felids, canids, raptors, and other primates. Antipredator behavior includes avoidance, mobbing, alarm calls, vigilance, evasive maneuver/fleeing/seeking refuge, and aggressive behavior based on level of risk.
Young animals are smaller and less experienced than adults and thus may be susceptible to a wider range of predators. This risk should lead to strong selection for the evolution of innate predator recognition yet examples of false alarming (alarming at nonpredators) by young primates suggest that this facet of antipredator behavior likely involves experiential refinement of the predator-recognition process. Studies of vervet monkeys, spectral tarsiers, and white-faced capuchin monkeys show that younger individuals alarm call at a wide range of harmless animals, a behavior rarely found in adults. As the individuals age, they become more selective and restrict alarm calling mainly to dangerous predators.

Meno et al. (2012) examined the influence of the social environment on antipredator behavior in infant, juvenile, and adult wild white-faced capuchin monkeys (Cebus capucinus) at Lomas Barbudal Biological Reserve in Costa Rica. Different species of model snakes and novel models. were presented to the capuchins and the authors examined: (a) the alarm calling behavior of the focal animal when alone versus in the vicinity of conspecific alarm callers and (b) the latency of conspecifics to alarm call once the focal animal alarm called. Focal animals alarm called more when alone than after hearing a conspecific alarm call. No reliable differences were found in the latencies of conspecifics to alarm call based on age or model type. Conspecifics were more likely to alarm call when focal individuals alarm called at snake models than when they alarm called at novel models. Results indicate (a) that alarm calling may serve to attract others to the predator’s location and (b) that learning about specific predators may begin with a generalized response to a wide variety of species, including some nonthreatening ones, that is winnowed down via Pavlovian conditioned inhibition into a response directed toward specific dangerous species. This study reveals that conspecifics play a role in the development of antipredator behavior in white-faced

MENO, W., COSS, R. G. and PERRY, S. (2012), Development of Snake-Directed Antipredator Behavior by Wild White-Faced Capuchin Monkeys: II. Influence of the Social Environment. Am. J. Primatol.. doi: 10.1002/ajp.22109

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