Raoul Schwing remembers sitting on a New Zealand mountaintop, watching a kea hovering in front of him, just an arm’s reach away. The large green parrot had jumped into an updraft, and was flying into the rushing air with such skill that it stayed in exactly the same spot. And then, it made an almost imperceptible shift in its wings, and shot off like a cannon. Keas do this a lot, and since they rarely hover more than a meter or so off the ground, they’re clearly not doing it for the view. Instead, Schwing says, they’re playing.
That might sound a bit anthropomorphic, were it not for, well, everything else about keas. These parrots are famed for their intelligence, curiosity, and vivacious nature. They’ll chase each other through the air, doing loops and spirals and wheeling side-by-side, before landing in the same spot from which they took off. They’ll toss a rock back and forth, like some kind of parrot tennis. They’ll sneak up and briefly grab each other by the feet. They’ll wrestle: One kea will lie on its back like a kitten, and another will jump on it.
Play—or activities of “limited immediate function,” in the words of the evolutionary psychologist Gordon Burghardt—is common in the animal world. Even reptiles, amphibians, and fish have been known to do it. But whether it’s to practice adult skills, or to coordinate the development of the growing brain, or to teach an animal how to be flexible in its actions, play tends to peter off during adulthood, and especially between individuals of the opposite sex. Adult wolves, coyotes, and African hunting dogs will play before a hunt. Chimps and bonobos play with potential mates. But in keas, both adults and juveniles play with each other in situations where neither food nor sex is in the cards.