The rook (Corvus frugilegus), a member of the crow family, seems to have developed a way to deal with the social stress of fighting, according to a study published in Current Biology this week.

Although birds of a feather flock together—and rooks are no exception—these birds also have their share of squabbles. In this study, researchers discovered that after two rooks fight both the bully and the victim often head straight to their mates for consolation, or something like it.

“It really looks like kissing,” says Amanda Seed, a Ph.D. student in experimental psychology at Cambridge University in the U.K. and co-author on the paper. “They lock the mandibles of their beaks and they sort of stroke each other’s beaks; and that’s what we call bill twining.” Post-conflict behavior like this is well documented in humans and other primates, but this is the first time it has been shown in birds.

Rooks never bill twine and make up with the bird they fought with, however. Seed and co-authors, Nicky Clayton and Nathan Emery, found this post-conflict behavior is limited to their mate, which differentiates them from primates.

So what is the purpose? Researchers aren’t sure. It may de-stress the birds after a conflict. “There is a cost to conflict and we know that it does affect aggressors and victims,” Seed says. “A stressed animal is not a healthy animal.”

But because the exact function of the behavior is largely unknown, there is debate about what to call it.  In chimps, similar behavior is called “consolation” or "reconciliation." But some researchers, such as Joan Silk, an anthropologist from University of California, Los Angeles, argue that these labels imply, perhaps incorrectly, that the animals process experiences like we do. Silk published an article in Current Biology on the subject this week.

In this study, Seed and co-authors named the behavior “third-party affiliation” to avoid that problem.

Regardless of what it is called, the behavior does seem to help birds navigate conflict. Seed says of the study, “It highlights this universality of the stresses of social living, which is familiar to all of us. And the birds have a way of trying to cope with that too.”

-Flora Lichtman

 

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