Unusual Behavior: Capuchin Monkeys Abduct Infant Howler Monkeys on Panamanian Island

On Jicarón Island in Panama, capuchin monkeys typically keep to themselves and do not interact closely with the neighboring howler monkeys. Therefore, the sight of a baby howler monkey riding on the back of a white-faced capuchin caught the attention of behavioral ecologist Zoë Goldsborough from the Max Planck Institute of Animal Behavior in Germany. She discovered this unusual behavior in 2022 while reviewing footage captured by remote cameras on the island.

After extensive observation, Goldsborough and her team concluded that young male capuchin monkeys on the island have repeatedly abducted infant howler monkeys, carrying them for several days at a time. Tragically, many of these young howlers succumbed to dehydration or starvation during these episodes.

Brendan Barrett, an evolutionary anthropologist and advisor to Goldsborough, described the footage as unsettling, likening the unfolding events to a horror story in progress. Both researchers, who are also affiliated with the Smithsonian Tropical Research Institute, usually study capuchin tool use rather than such distressing behavior involving infant monkeys.

Between January 2022 and July 2023, the team recorded 11 instances of howler monkey infants being carried by five different juvenile male capuchins. This behavior appears to have originated with a particular male nicknamed Joker, identifiable by a small scar near his mouth, with other young capuchins mimicking his actions months later.

Neither the researchers nor independent experts reviewing the findings believe the capuchins intentionally harm the infants. Barrett compared the young capuchins' actions to children catching fireflies and unintentionally causing their death by keeping them confined.