Agencies PANAMA

Scientists studying monkeys on a small Panamanian island have uncovered a bizarre and unprecedented phenomenon: capuchin monkeys are "kidnapping" baby howler monkeys, carrying them on their backs despite being unrelated and different species.

Researchers from the Max Planck Institute of Animal Behavior and the Smithsonian Tropical Research Institute, who had set up cameras to study capuchin tool use, were shocked to discover video footage showing at least 11 instances of capuchins carrying howler infants between 2022 and 2023.

"This was very much a shocking finding," said Zoë Goldsborough, a behavioral ecologist at the Max Planck Institute of Animal Behavior. "We've not seen anything like this in the animal kingdom." The motivations behind these abductions remain a mystery. Capuchin monkeys, known for their intelligence and ability to learn new behaviors, are small, house cat-sized primates native to Central and South America.

Initially, researchers believed they were witnessing a "heartwarming story of a weird capuchin adopting these infants," especially after one subadult male, nicknamed "Joker," was seen carrying multiple howler babies. However, as more cases emerged involving different capuchins, it became clear this wasn't a simple adoption. The footage shows the capuchins carrying the baby howlers, sometimes while also using stone tools. The abductions themselves likely occurred in the trees, where howlers primarily reside.

Grim Outcome for Abducted Infants Tragically, researchers believe that in most, if not all, cases, the abducted howler babies died, likely from starvation. The infants, ranging from a few weeks to a few months old, were too young to be weaned and relied on their mothers for nursing. "A hopeful part of me wants to believe some escaped and went back to their mothers, but we don't know," said co-author Margaret Crofoot.