Capuchin monkeys kidnap howler monkey babies, video reveals

▲ A young howler monkey clinging to an adult male capuchin on Jicarón Island, Panama. AP Photo

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La Jornada Newspaper, Wednesday, May 21, 2025, p. 6

Washington. A baby monkey clung to the back of an older male primate, its tiny fingers gripping the fur. But they're not related, and they're not even the same species.

Scientists found startling evidence of what they describe as monkey abductions while reviewing video footage from a small island in Panama. Capuchin monkeys were observed carrying at least 11 howler monkey offspring between 2022 and 2023.

"This was a very striking finding ," said Zoë Goldsborough, a behavioral ecologist at the Max Planck Institute for Animal Behavior in Germany. "We haven't seen anything like this in the animal kingdom ."

The monkeys' motivations are still under investigation. Capuchins are cat-sized monkeys found in South and Central America. They are long-lived, intelligent, and learn new behaviors from each other. A group of capuchins in Panama has even learned to use stone tools to crack open nuts and shellfish.

Goldsborough and other researchers from Max Planck and the Smithsonian Tropical Research Institute had set up more than 80 cameras to study capuchin tool use, but were surprised to see the first howler pups appear in early 2022.

The footage showed the capuchins walking and using their stone tools while carrying baby howlers on their backs. But the cameras didn't capture the abduction moments, which scientists said likely occurred in trees, where howlers spend most of their time.

Our view of this history is limited , said co-author Margaret Crofoot of Max Planck and the Smithsonian. The findings were published in the journal Current Biology .

In most or all cases, the howler monkey babies died, the researchers said. Infant howler monkeys would normally be carried by their mothers while they were still nursing. All of the infants in the video, ranging from a few weeks to a few months old, were too young to be weaned.

A hopeful part of me wants to believe that some escaped and returned to their mothers, but we don't know , Crofoot said.

Videos recorded some cases of young capuchin males still carrying howler monkey offspring that had died, likely from starvation. Many animals, from gorillas to orcas, have been observed carrying their own dead offspring, although scientists are unsure of the reasons.

Why did the capuchin males do this? There were no signs of deliberate aggression toward the young, and they were not eaten, which rules out predation.

We've spent hours racking our brains over why they would do this , Goldsborough said.

The first capuchin chick-snatcher may have had a confused caregiving motivation , or paternal instinct, because he displayed gentleness when interacting with the infants, she explained. Other males later copied his actions.

Researchers said they don't believe the capuchins have intentionally harmed the babies. So far, only one group of capuchins has been known to kidnap.