From NPR.

A group of monkeys on an island in Panama are stealing babies from another monkey species that lives nearby, seemingly just for kicks, a fad that one researcher called “viscerally disturbing.”

This island group of capuchin monkeys is known to be inventive — unlike capuchins on the mainland, they use stone tools to break open hard food items. Researchers were studying this tool use with wildlife cameras, and the cameras saw a young male capuchin carrying around a baby from a different species — a howler monkey. The capuchin did this repeatedly, carrying several howler babies until they died; then other immature males in the group started snatching howler babies too.

In the journal Current Biology, researchers say they believe the kidnappings started as a way to combat boredom on an island that has a lot of food and no predators — they say they can’t see a reason for the kidnappings. The activity they caught on video shows how this species has a strong urge to try new things, and to copy each other.