Among New World primates, capuchin monkeys are the most generalist eaters, including a great
diversity of food items in their diets. In the last decades, vertebrate consumption by different species of
capuchin monkeys has received attention, considering the hypothesis that it may represent an
alternative or complementary nutritional resource to fruits, or even invertebrates. In the present study,
field data on vertebrate consumption (mammals, reptiles and avian prey) by two groups of wild
bearded capuchin monkeys (Sapajus libidinosus) living in Fazenda Boa Vista (FBV, Piauí State, Brazil)
were collected through scan sampling and ad libitum methods, and analyzed via non-parametric tests
across sexes and age classes, in the dry and the wet seasons. During 48 months (5798 observation
hours from May 2006 to December 2010), we recorded 280 events. In 230, only one individual was
involved (type 1), whereas in 50 events two or more individuals were involved (type 2). Males engaged
in more vertebrate consumption events than females, although significant differences were only found
in type 2 events (P<0.01). Sexual dimorphism, dominance interactions, or sexual differences in
nutritional demands may have contributed to the obtained results. Adults and juveniles performed most
of the consumption events of both types (type 1 events: P<0.01; type 2 events: P<0.01), and reptiles
were the most consumed prey (type 1 events: P<0.01; type 2 events: P<0.05) - the monkeys
frequently ate their brain and viscera. Vertebrate consumption occurred mainly in the wet season (type
1 events: P<0.01; type 2 events: P<0.05), when food is abundant. Therefore, the predatory activity of
capuchin monkeys in FBV appears opportunistic and possibly dependent on vertebrate prey
abundance, rather than a food alternative during periods of low fruit availability.
