Plain-tailed wrens (Pheugopedius euophrys) routinely sing in duets. This isn’t so unusual for birds conducting mating displays. What is unusual is that the birds seem hardwired to cooperate with one another. Not only is the combined song almost indistinguishable from a single voice, but the birds strongly prefer the duets to any other sounds, including their own individual songs.
Eric Fortune from Johns Hopkins University led a team of researchers to the cloud forests of Ecuador to study the songs of plain-tailed wrens. The birds sing in male-female pairs, with the two partners alternating notes so tightly that they sound like a single bird. When captive wrens were subjected to brain scans, the scientists discovered that each bird’s neurons fired more strongly when exposed to the duet than to that bird’s own part of the song.
Because all vertebrate brains are similar at some level, the scientists believe this finding will have implications for the evolution of cooperation. As Fortune states:
Brains among vertebrate animals—frogs, cats, fish, bears, and even humans—are more similar than most people realize. Thus, the kinds of phenomena that we have described in these wrens are very relevant to the brains of most, if not all, vertebrate species, including us humans.
You can watch Fortune’s explanation below:
For more clips showing each bird’s part in the duets, click here.