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Monkeys on a remote island have shocked scientists with their never-before-seen behaviour. A behavioural ecologist captured a capuchin monkey carrying a small figure on its back on her camera trap footage, but something didn't seem right.
At first, Zoë Goldsborough thought it was just a baby capuchin, but soon realised it was not the right colour. She sent a screenshot of the footage to her research collaborators who were also left confused. It soon turned out that the monkey was actually carrying a baby howler - a monkey of a different species.
As reported by CNN, Goldsborough said: "I realized that it was really something that we hadn’t seen before. I was shocked." The scientists use hidden camera traps, that are motion-triggered, because Jicarón Island is uninhabited by humans.
She then searched through the rest of the footage, which was collated over 15 months on a research site on the island located 34 miles off the coast of Panama, to uncover a bizarre trend. The white-faced capuchin monkey, nicknamed "Joker" due to the scar on his mouth, was captured carrying a baby howler monkey in other clips taken on the island.
Goldsborough also noticed other male capuchins doing exactly the same thing. Her collaborators from the Max Planck Institute of Animal Behavior, University of Konstanz, and Smithsonian Tropical Research Institute, then launched a study to find out why they were doing it.
They found that, between January 2022 and March 2023, four capuchin monkeys had abducted at least 11 infant howler monkeys. They concluded the behaviour was a "cultural fad" as there was no evidence that the capuchins were caring for or playing with the infants.
According to the IUCN Red List of Threatened Species, the howler population on Jicarón is an endangered subspecies. However, their mothers give birth only once every two years.
Goldsborough said the case "was kind of like a roller coaster where we kept having different interpretations, and then we would find something that proved that wrong."
While monkeys are known to "adopt" abandoned infants, it became clear to the scientists that Joker was just carrying them on his back. Pedro Dias, a primatologist at Veracruzana University in Mexico, said it was odd as he was not feeding them or caring for them.
Instead, the capuchins just carried the howlers around for a few days. They didn't play with them, show interest in them, or act aggressively.
The scientists proposed that the capuchin monkeys on the island might just be a bit bored. They didn't abduct the baby howlers to care for or to harm.
The scientists explained that boredom could be a key driver of innovation. This is heightened among young male species of the monkey, who have previously been observed using stones to crack nuts.
Much like temporary fads among humans, Goldsborough hopes this behaviour of the capuchins will fade. It's also possible that the howler monkeys will begin to adapt their behaviour to protect their babies.
Brendan Barrett, a behavioral ecologist and Goldsborough’s adviser, said: "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."
English (US) · 