The kea of New Zealand is the first non-mammal species to demonstrate infectious laughter, a new study says.
The highly intelligent parrot has a specific call, that—like human laughter—puts other parrots that hear it in a good mood. This makes the kea the first known non-mammal to show contagious emotion, joining the ranks of humans, rats, and chimpanzees.
Scientists already knew that kea—native to New Zealand's mountainous South Island—make a non-threatening warbling sound while playing with other kea. But since the birds also warble alone, the noise could simply be an expression of pleasure.
“In many instances, we saw that the kea were immediately animated to play, but not by joining ongoing play already happening,” Schwing says in an email.
“Instead, they spontaneously started to play with the bird next to them, or played solitarily in the air or with an object.” (Related: "Fun and Games Led to Some of the World's Greatest Inventions.")
This suggests that the play call does not "invite" kea to play, but rather puts them in a frisky frame of mind by affecting their emotions. For that reason, kea play calls can be compared with infectious laughter in people, according to the study, published March 20 in the journal Current Biology.