RESUMO
We report the killing of a snake (Philodryas nattereri, Colubridae) by a blonde capuchin monkey (Sapajus flavius, Cebidae). This endemic primate species from the northeast of Brazil includes vertebrates such as lizards and marsupials in its diet, but we can find no previously published record of an attack upon or consumption of snakes by this species of platyrhine monkey. During the attack, the group mobbed the snake, with individuals uttering agonistic vocalizations and displaying behaviors such as raising their tails, moving tree branches, piloerecting, and baring their teeth. An adult male monkey seized the snake, bit and twisted its body, thereby killing it; he then dropped the carcass onto tree branches, but did not consume it. This single event suggests that this Cebidae species may be able to distinguish dangerous from harmless snakes, and it also may be an example of a lethally violent reaction to a potential predator or competitor, exemplifying the plasticity and cognitive skills exhibited by genus Sapajus.