Not all male partners are bad listeners. When male plain-tailed wrens sing complicated interweaving duets with females, their brains buzz with so much activity that it’s likely that they pay more attention to her contribution to the melody than their own. The same can’t be said of their partners, however.
Plain-tailed wrens (Pheugopedius euophrys) live in South America. When males and females duet, they switch between singing and listening so quickly that the resulting melody sounds like a solo.
To find out more about the birds, Eric Fortune at Johns Hopkins University in Baltimore, Maryland, and colleagues headed to the cloud forests of Ecuador to record over 150 hours of birdsong.
Wrens mostly duetted, but Fortune noticed that the occasional lonesome bird would sing a solo, leaving silences when a partner would usually pick up the melody. Curiously, these soloists left longer silences than would be expected during a duet, as if they were waiting for a cue to take the melody again. This suggests that coordination and cooperation is an intimate part of the duets, says Fortune.
Bird on a wire
To probe further, he captured six wrens â€“ three females and three males â€“ that he had earlier recorded singing with their partners in the wild. Fortune anaesthetised each bird and inserted a thin wire into an area of the brain dubbed the high vocal centre (HVC), which is involved in both learning and producing birdsong.http://www.newscientist.com/article/dn21123-male-wren-more-alert-to-females-song-than-his-own.html
While the birds were unconscious, Fortune played them several tunes, including their duet with their partner, snippets of the duet containing just their own or their partner’s song, and artificial duets cobbled together by editing the original melody.
Fortune expected brain activity to ramp up when the birds heard their own part, because they were most familiar with it. But in both sexes activity was most rampant when the birds heard the full duet. Even hearing a similarly complicated â€“ but artificial â€“ duet did not result in such strong activity. “The strongest memory they have is of the combined performance,” he says. “This is why they duet so effectively: cooperation is encoded in their brain.”
Intriguingly, even though males never sing the female part, activity in their HVC was higher when listening to a female croon than when listening to his own song. For the female, however, listening to herself produced more neural activity than listening to her partner sing. It’s a “truly crazy result”, says Fortune, which suggests that it is more important for these males to pay attention to the female’s tune than their own sounds.
“The underlying neuroscience of duetting has been completely neglected so far,” says Michelle Hall at the University of Melbourne, Australia. This finding suggests that coordinated action such as duet singing strengthens the bond between partners.
“Perhaps there is a lesson in the brain of the wrens that might help male humans,” says Fortune.