White-Faced Capuchins Cooperate to Rescue a Groupmate from a Boa constrictor

Abstract

Although avoidance of predators has long been thought to play a major role in the evolution of primate sociality [van Schaik, 1983], there are relatively few data on predation attempts on primates and the responses of primates to attacks by predators [Stanford, 2002]. Wild white-faced capuchins (Cebus capucinus) regularly mob snakes [Chapman, 1986]. There is one published observation of whitefaced capuchins killing a Bothrops asper with a club [Boinski, 1988], and one published account of successful predation by a Boa constrictor on a juvenile whitefaced capuchin [Chapman, 1986]. In the latter instance, the victim’s groupmates mobbed the snake and one adult male repeatedly dropped a stick on it, but none of the monkeys tried to use contact aggression to free the victim. On July 13, 2002, while conducting a study on infant development in C. capucinus at Lomas Barbudal Biological Reserve, Costa Rica, we observed an attack by a 2-m-long Boa constrictor on a 3-year-old capuchin (MH). By the time the observers arrived on the scene, the boa was coiled around MH. Her mother, MA, arrived almost immediately and was soon joined by another juvenile. MA repeatedly bit the snake and pulled at it, uncoiling its tail and body from the victim. Meanwhile, alpha-male PP arrived and began hitting and perhaps biting the snake from the opposite side, so that the snake could not defend itself from MA and PP simultaneously. The juvenile who was first to arrive grabbed MH’s arms and pulled