Keas just want to have fun Mark Taylor/naturepl.com

If your parrot is feeling glum, it might be tweetable. Wild keas spontaneously burst into playful behaviour when exposed to the parrot equivalent of canned laughter – the first birds known to respond to laughter-like sounds.

The parrots soared after one another in aerobatic loops, exchanged foot-kicking high fives in mid-air and tossed objects to each other, in what seems to be emotionally contagious behaviour. And when the recording stops, so does the party, and the birds go back to whatever they had been doing.

We already knew that these half-metre-tall parrots engage in playful behaviour, especially when young. What’s new is that a special warbling call they make has been shown to trigger behaviour that seems to be an equivalent of spontaneous, contagious laughter in humans.


Moreover, it’s not just the young ones that respond, adults of both sexes join in the fun too.

Listen up

Raoul Schwing of the University of Veterinary Medicine in Vienna, Austria, and his team played 5-minute recordings to gatherings of between two and a dozen wild keas on a mountainside of New Zealand’s Arthur’s Pass National Park, on the southern island.

The group played recordings of the warble sound, or other sounds, including two other frequent kea sounds – a screech and a whistle – plus the alarm call of a local robin species and a bland tone.

For each test, Schwing’s team monitored and videoed the birds’ behaviour from 5 minutes before until 5 minutes after the recording, noting any unusual antics while the recording played. In all, they conducted 60 tests, one-third of them with the warble sound.

The birds went into play mode when they heard the warble recordings. “On hearing the calls, many birds started to spontaneously play with non-playing birds, or with an object close by, or by performing aerial acrobatics,” says Schwing.

The average number of play bouts per bird monitored was 20 times higher during those periods than when birds heard the other recordings. Likewise, the average length of play per bird was 90-fold longer during the warble recordings.

Contagious fun

Schwing says the observations reveal close parallels between the emotional contagion caused by the warbles in parrots and by laughter in humans.

The contagious behaviour resembles the glee-like excitement that can spread among young children, rather than, say, infectious laughter after a joke. “Further research is needed to look for other effects the play call might have that parallel other effects of human laughter,” he says.

It means that humans and their closest relatives might not be the only species capable of emotional contagion spread by sound.

“The only other animals to show this contagion effect are chimpanzees and rats, both very or relatively close in evolutionary terms,” says Schwing. “Our finding further bridges the perceived gap between humans and [other] animals, and shows that it also happens in birds, which are very distantly related.”

Play it again, Polly

Other researchers agree that the team’s evidence supports the idea that the warbles can trigger fun-loving behaviour.

“For many years, I’ve noted that play among dogs and other mammals is socially contagious, and that individuals who hadn’t been observed to play previously often begin playing when they see other individuals romping around and having fun,” says Marc Bekoff of the University of Colorado in Boulder.

“It’s equally important that they discovered that individuals not likely to play – mature individuals of the opposite sex – also respond when they hear the call,” says Bekoff.

Sophie Scott of University College London says this is the first demonstration of a functional role for play calls in birds.

“The play calls seem to be linked to both solitary and social play behaviours, and importantly they seem to be contagious,” she says. “It is a genuinely exciting demonstration of behavioural and, arguably, emotional contagion.”

Journal reference: Current Biology, DOI: 10.1016/j.cub.2017.02.020

Read more: 10 Mysteries of you: Laughter; Laughter’s secrets: No funny business; The secrets of laughter