In a bizarre phenomenon observed on a Panamanian island, a group of juvenile capuchin monkeys has been kidnapping infants of another monkey species, leaving scientists perplexed. Camera trap footage from Jicarón Island revealed a male capuchin monkey, nicknamed “Joker,” carrying a howler infant on its back, sparking an investigation into this unusual behavior.
Behavioral ecologist Zoë Goldsborough first spotted the unusual figure on the capuchin monkey’s back in camera trap footage. Initially thought to be a baby capuchin, further observation revealed the figure’s unexpected coloration, indicating it was actually a baby howler monkey. “I realized that it was really something that we hadn’t seen before,” Goldsborough said. As she searched through more footage, she noticed Joker and other male capuchins carrying baby howler monkeys, with no apparent reason or benefit to themselves.
Goldsborough’s team studied 15 months of camera-trap footage from Jicarón Island and found that four subadult and juvenile male capuchin monkeys had abducted at least 11 infant howler monkeys between January 2022 and March 2023. With no evidence of the capuchins eating, caring for, or playing with the infants, the researchers suspect this behavior is a kind of “cultural fad” – potentially driven by the monkeys’ unique island environment.
Several theories have emerged to explain this behavior, including boredom, over-imitation, and cultural innovation. The island’s lack of predators and relative safety may allow the capuchins to explore and engage in arbitrary behaviors. The capuchins might be imitating Joker’s behavior as a way to socially bond with him, or younger individuals may be more prone to innovative behaviors. However, the researchers are concerned about the impact on the endangered howler monkey population.
“It’s possible that the capuchins’ kidnapping behavior is similarly arbitrary — if not moderately entertaining for them,” said study coauthor Brendan Barrett. The team hopes this behavior will fade away or that the howler monkeys will adapt to protect their babies. As Barrett noted, “It kind of is like a mirror that reflects upon ourselves, of us seemingly doing things to other species that can harm them and seem atrocious that have no real purpose.” This phenomenon highlights the complexities of primate behavior and the need for further research into the intricacies of island ecosystems.
Key Findings:
- Number of Kidnapped Monkeys: At least 11 infant howler monkeys were abducted by capuchin monkeys.
- Duration: The kidnappings occurred over 15 months, from January 2022 to March 2023.
- Location: Jicarón Island, Panama.
- Researchers’ Concern: The impact on the endangered howler monkey population.