Why otters ‘juggle’ rocks is still a mystery
A lovely, intuitive idea about why otters juggle rocks — that it helps them practice survival skills — might not be correct, new tests show. The term “juggling” is itself overenthusiastic. Otters don’t keep stones flying around in some tall, aerial circle. Instead, the animals shuffle rocks back and forth quickly between their front paws. “It’s very close to the body,” says animal behaviorist Mari-Lisa Allison, who studied the behavior as a graduate student at the University of Exeter in England. Such deft fiddling looks as if it might make a great example of how animal play could serve as practice for real-life challenges. In the wild, small-clawed otters need paw dexterity to tweak shreds of seafood out of crustacean or mollusk shells. And yet, three kinds of tests found no evidence that juggling builds otters’ food-picking skills, Allison and her colleagues report May 6 in Royal Society Open Science. The question of how play evolved (SN: 2/6/18) has long fascinated biologists. According to the latest thinking, play...