Capuchin monkeys caught on camera kidnapping howler monkey babies

Capuchins caught on camera carrying howler monkey babies (Image: AP)

A tiny howler monkey, fingers curled into fur, clung tight to a capuchin’s back. It looked like a sweet moment of monkey bonding—until scientists realised the pair weren’t even the same species. And worse, the baby was not going to survive.

Researchers studying monkey behaviour on a small island in Panama were stunned to uncover a rare phenomenon. Hidden in video footage from 2022 to 2023, they spotted capuchin monkeys carrying at least 11 infant howler monkeys. The species are unrelated and not known to interact closely.

The footage came from over 80 cameras placed by scientists from the Max Planck Institute of Animal Behavior and the Smithsonian Tropical Research Institute. These were originally set up to study how capuchins use stone tools to crack open nuts and seafood.

This photo provided by researchers shows a baby howler monkey clinging onto a young adult male capuchin monkey on Jicarón Island, Panama in September 2022. (Brendan Barrett/Max Planck Institute of Animal Behavior via AP)

Unexpected Behaviour Stuns Scientists

Dr Zoë Goldsborough, a behavioural ecologist with Max Planck, said the findings came as a huge surprise. “We’ve not seen anything like this in the animal kingdom,” she explained.

The camera traps captured capuchins walking with baby howlers on their backs. Sometimes, the capuchins were even seen hammering their tools while carrying the infants. However, the actual moment of abduction was never recorded. Researchers believe it likely occurred in the treetops, where howlers usually live.

 (Brendan Barrett/Max Planck Institute of Animal Behavior via AP)

Capuchin monkeys are about the size of a house cat. Native to Central and South America, they are intelligent creatures who often learn behaviours from each other. On this particular island, one group is already known for its rare tool-using habits.

The study, published Monday in the journal Current Biology, raises more questions than it answers.

Mystery Behind the Kidnappings

Tragically, most of the baby howlers died. The infants seen in the videos were still too young to be weaned. Under normal conditions, they would be nursing and clinging to their mothers.

Co-author Dr Margaret Crofoot said, “A hopeful part of me wants to believe some escaped and went back to their mothers, but we don’t know.” In some footage, young capuchin males were still carrying dead howler babies, likely victims of starvation.

Animals such as gorillas and orcas are sometimes seen carrying their dead offspring. However, the reasons behind this behaviour remain unclear. In this case, there were no signs of violence or cannibalism, making the behaviour all the more baffling.

“We’ve all spent hours wracking our brains why they would do this,” Goldsborough said. One theory is that the first male may have had a misdirected parenting instinct. He showed gentle behaviour towards the infants. Then, four other males appeared to imitate him.

So far, only one specific group of capuchins has displayed this behaviour. Scientists don’t believe the monkeys acted out of harm or aggression.

Insights Into Monkey Minds

The strange behaviour offers a rare look at the emotional complexity of these animals. Catherine Crockford, a primatologist at the CNRS Institute for Cognitive Sciences in France, called it an example of “remarkable behavioural variation” within a species. She was not involved in the study but found the findings noteworthy.

The research has left experts with more questions than answers. But one thing is clear: even in the animal world, instincts can sometimes take an unexpected turn.