Moment monkey 'kidnaps' a baby of another species and carries the bub away on its back... and experts are struggling to work out why

Daily Mail​

20-05-2025

Fascinating new video footage captured on a remote island has captured a bizarre new phenomenon - baby monkeys being abducted by another species.
The unprecedented craze of so-called 'monkey kidnappings' by capuchin monkeys have left scientists baffled, having first discovered the distinctive behaviour while reviewing footage from the small island of Panama.
Zoe Goldsborough, alongside other researchers at Max Planck and the Smithsonian Tropical Research Institute in Germany, had initially set up more than 80 cameras to study capuchin tool use, but were shocked to witness the first howler babies begin to appear in early 2022.
In bewildering new footage shared on YouTube a capuchin monkey, the size of a house-cat, is videoed with a baby howler monkey clinging to its back. Neither monkey are related, nor even of the same species.
In fact, over the course of the 'tends and thousands of video footage and images', the all-male capuchin monkeys were seen carrying at least 11 howler babies between 2022 and 2023.
Ms Goldsborough described the kidnappings as a 'shocking finding', with it still unclear what motivated the monkeys to carry out the mass abductions.
Stressing the unprecedented nature of the footage, she added: 'We've not seen anything like this in the animal kingdom.
'We could see, for instance, that it was not a case of adoption where these babies were found by the capuchins, but rather abduction, because the infants tried to escape, they called to their parents who called back and we also saw the capuchins preventing them from escaping.'
Meanwhile, Margaret Crofoot, co-author of Max Planck and Smithsonian, who have published the findings from the study in the Current Biology journal, described the early photographs of the kidnappings as 'so weird and so wrong'.
The fascinating video showed the capuchins walking and pounding their stone tools with baby howlers on their backs.
However, cameras did not capture the moments of abduction, which scientists said likely happened up in the trees, where howlers spend most of their time.
As a result, Ms Crofoot described their 'window' into the story as 'constrained'.
In most or all cases, the baby howlers died, the researchers said. Infant howler monkeys would normally be carried by their mothers while still nursing.
All the babies in the video - from a few weeks to a few months in age - were too young to be weaned.
Ms Crofoot added: 'A hopeful part of me wants to believe some escaped and went back to their mothers, but we don't know'.
The videos recorded a few instances of young capuchin males still carrying howler babies that had died, likely from starvation.
Many animals - from gorillas to orcas - have been observed carrying their own dead offspring, though scientists are unsure of sure the reasons.
Found solely in South America and Central America, the capuchin monkeys are long-lived, intellectual and often learn new behaviours from each other.
One particular group of capuchins in Panama even learned how to use stone tools to crack open nuts and seafood.
But, the question still remains - Why did the capuchin males do it? There were no signs of deliberate aggression toward the babies and they weren't eaten, ruling out predation.
Ms Goldsborough said that the scientists have 'all spent hours wracking our brains why they would do this'.
The first baby-snatcher may have had a confused 'caring motivation,' or parental instinct, because he showed gentleness interacting with the infants, she said. Then four other males copied his actions.
Brendan Barrett, project leader for the Department for Ecology of Animal Societies, said that given there was no utility or function of the kidnapping, the monkeys may have been doing it simply out of 'boredom' given there is a lot of 'free time' on islands.
The researchers said they don't believe the capuchins harmed the babies on purpose. So far, only one other group of capuchins has been known to kidnap.
The research shows the 'remarkable behavioral variation across social groups of the same species,' said Catherine Crockford, a primatologist at the CNRS Institute for Cognitive Sciences in France, who was not involved in the study.