Some male capuchin monkeys in Panama have developed a new behaviour where they abduct baby monkeys of a different species and carry them around for days without providing care.
This was according to a report published in the journal Current Biology on Monday.
The Panama capuchin monkeys on Jicarón Island in Panama have been observed with a series of cameras since 2017.
The group are known to use stone tools to crack hard nuts and shellfish.
While reviewing video footage, Zoë Goldsborough from the Max Planck Institute for Behavioural Biology in Germany noticed a young male carrying a small howler monkey baby.
Mr Goldsborough combed through the year’s footage and found four howler monkey babies had been carried.
Most of them were by a young male nicknamed “Joker”, who was first seen with an infant in 2022.
“We came to the conclusion that it must be a single individual trying something new,” said Brendan Barrett.
Mr Barrett is the group leader at the institute. He said it was not unusual, as the monkeys are curious.
Five months later, new images and videos showed baby howler monkeys carried by other capuchins, which turned out to be four more young males besides Joker.
Researchers initially considered whether the monkeys might be attempting adoption, but the males showed no signs of caregiving and did not even play with the abducted offspring.
The 15 months of footage showed at least 11 abducted howler monkey infants being carried for up to nine days.
Four were later found dead, and none of the others is believed to have survived.
It is unclear how the capuchin monkeys abducted the howler monkeys.
“The capuchins didn’t harm the babies, but they could not provide the milk the infants needed to survive,” Mr Goldsborough said.
The scientists said the capuchins, which live in a predator-free environment, appear highly curious and prone to experimenting with new behaviours.
Although no clear reason for the abductions was found, the researchers suggest the actions may have been driven by boredom.
