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.
By studying these birds, Schwing also realized that they have a “play call”—a warbling noise that they make while they’re playing. And the call isn’t just a statement. It’s also a trigger. It seems to induce playfulness in other keas within earshot; when they hear it, they also start playing with nearby peers. It has an infectious quality—just like human laughter. “When kids play and laugh, other kids want to play more,” says Schwing. “And this still exists in adults: That’s why American sitcoms have laugh tracksTo appreciate this, watch an episode of Friends without the laughter track; it is intensely creepy..”
Schwing first became interested in keas four years ago because they’re such unusual birds. They perch on an ancient branch of the parrot family treeThe closest relatives of the parrots are, surprisingly, the falcons. Keas have several physical features that are uncannily falcon-like.: Around 56 million years of evolution separate them from other parrots like macaws or budgies. They’re very intelligent. In one study, a captive kea named Kermit successfully solved a logic puzzle in the most kea-like way possible—by rambunctiously attacking the problem until he found a solutionNot all keas are masterminds, though. In a zoo in Amsterdam, I once saw a kea try to lift a tray that was concealing some food—while standing on the tray.. And they’re intensely curious, with a penchant for approaching tourists, stealing food, investigating bags, and wrecking cars. When I travelled to New Zealand, a kea tried to pry the rubber off my tires.
Unlike other birds, which shy away from new and unfamiliar objects, keas are drawn to novelty like moths to flame. Schwing once demonstrated this by asking one of his colleagues at the University of Vienna to shine a bicycle light at some captive ravens. Even though he had hand-raised those birds, they fled when the light came on. But when he did the same to captive keas, half the birds immediately flew over to investigate. This makes them very easy to study in the wild. “For most birds, you need hides and blinds,” says Schwing. “But if you see a kea flying in the distance, you can make as much noise as possible and wave things around, and they’ll make a beeline for you.”
Schwing started his work by building a library of kea calls. After two years and a lot of recording, he realized that the calls fell into seven categories, and that one of them was only ever made during play. To understand its role, Schwing and his colleagues took some speakers into the mountains and played one of five possible recordings: the kea play call, two other kea calls, the call of another local bird, or a simple standardized tone. They found that the play call—and only the play call—made keas more playful. For five minutes, they played more frequently and for longer bouts than the minutes immediately before. And once the recordings stopped, so did the play.
When the birds heard the call, some of them would join in play that was already underway. But many just started playing with the kea that was standing next to them, which was also not playing. And if there’s no other kea around, they’ll just play on their own, throwing rocks or performing aerobatics. Schwing sees human laughter as the closest analogy because both the call and laughter are positive behaviors that temporarily triggers something similar in other listeners.
Again, that might seem anthropomorphic, but Schwing’s going with it, partly because similar kinds of “positive emotional contagion” have been found in two other species—rats and chimps—and in both cases, the scientists involved “immediately called it laughter,” he says. “Hearing people laugh puts us in a better mood but also increases the humor that we perceive in certain things,” he says. “But of course, you’re not compelled to do somersaults, so the play call isn’t exactly like this.”
“Importantly, the play behaviors stop quite quickly, so it doesn’t look likely that the call is simply putting the kea in a good mood,” says Alex Taylor, from the University of Auckland. “It looks more like an automatic, emotional reaction, similar to how humans react to a canned laughter track, rather than a change in mood, such as when we feel good for a few hours after visiting a comedy club.”
But Elodie Mandel-Briefer, from ETH Zurich, points out that many animal calls can lead to similar behavior—alarm calls that trigger alarm or aggressive calls that trigger aggression. To definitively show that the kea play calls are also transferring emotions, rather than simply cueing similar actions, Schwing would need to find some way of measuring the emotional state of both the callers and listeners, she says.
Schwing is more focused on working out why the birds are so playful in the first place. He thinks it has something to do with their intensely social natures, and their almost utopian societies. Keas will gather in hotspots of up to 30 birds, and they’ll mingle in very fluid groups. They don’t have any obvious pecking orders. And they are extraordinarily peaceful. “I have seen somewhere around 15 and 25 percent of the entire kea population, and in four years, I have never seen adults fighting,” Schwing says.
He believes that keas play so extensively to increase tolerance within their groups. As he puts it: “We wrestle for fun, and now we’re buddies, so we can eat from the same food and we don’t care.” And he’s going to do some experiments to test this idea. “Maybe if we play back the play call to captive keas who are less playful, we’ll find that half an hour later, they’re still more tolerant of others, and more willing to share food.”
Most kea research “has focused on their problem-solving skills,” says Megan Lambert, from Lund University, “and there hasn’t been a whole lot of research on their social lives. They’re great candidates for social cognition studies so hopefully this will prompt further research in this field.”
But as with many plans to study wild behavior, this one comes with a timer. Keas are endangered, with only 1,000 to 5,000 of them left in the wild. Although they mainly feed on plants and insects, they’ll eat meat when given the chance; some have been known to scavenge off dead sheep, or even flay fat from the backs of living livestock. For that reason, farmers put bounties on their heads, and more than 150,000 of the birds were shot before they gained protected status in 1986.
They still face many dangers. Introduced predators like possums will eat their chicks and eggs. Pest control traps poison them, as does lead from building materials and ammunition. Several projects are now underway to protect the birds, and to avert a future when the last, lonely kea jumps into an updraft, hovers with delight, makes a play call, and gets only silence in response.