Capuchin Monkeys Turn to Small Prey When Plant Foods Run Short

Bearded capuchin monkeys appear to rely more heavily on hunting when their usual plant foods become difficult to find, according to a study published in PLOS One and reported by Phys.org. Researchers observed two groups of capuchins at Fazenda Boa Vista in Brazil between 2006 and 2010, recording more than 5,000 hours of behavior. During that period, they documented 446 instances in which the monkeys ate small animals. Lizards accounted for 43% of those observations, while rodents made up 28%. The researchers also recorded what the source describes as the first documented cases of these capuchins eating opossums, iguanas and bird nestlings. Hunting was not evenly distributed across the groups: males pursued prey more often than females and were more likely to target potentially dangerous animals, including snakes. The availability of plant food also appeared to matter. Hunting increased when fruits and vegetables were less accessible, suggesting that the monkeys turned to animal prey under conditions of food scarcity. The capuchins often focused on the brains and internal organs of their prey, behavior the researchers interpreted as a possible preference for tissues rich in fat. The findings may offer a limited comparison for studying human evolution. Humans are the only living primates known to regularly hunt animals larger than themselves, but the researchers said predation by early humans may have developed from eating smaller animals. The capuchins’ behavior suggests that small vertebrates could provide an important source of nutrition when plant foods were limited. The authors cautioned that further research is needed to test whether the same patterns occur in other capuchin groups and primate species. They also suggested that fossil evidence from early humans could be reexamined for signs of small-vertebrate hunting. Susana Carvalho of Gorongosa National Park, one of the study’s lead authors, emphasized the value of long-term observations. The source reported that the 45 months of data revealed a clearer pattern than shorter studies might have: lizards, rodents and snakes became important foods when fruit was scarce, while the monkeys showed particular interest in energy-dense body tissues.