He knows she’s listening. And now we know that she knows he knows.
Using the word “know” loosely, that’s a simplified version of a new analysis of zebra finches by neuroscientists at the University of California, San Francisco.
Sarah Woolley explains that males sing a song differently when they’re in front of females than when they’re just twittering to themselves. Now she and Allison Doupe have found that females prefer the ladies-are-listening version. An area of the female brain associated with processing social context gets especially active during the males’ formal serenades, Woolley and Doupe report in the March PLoS Biology.
Songbirds are among the few animals known to learn their communication skills. So studying birds could offer insights into human communication and learning.
The new research looks at directed communication, in which the sender of the message focuses on a particular audience. People talking to babies typically fall into an exaggerated lilt, and studies show that babies pay more attention to the more melodious version. Male canaries tend to add special syllables to their courtship songs when strutting in front of a female, and females prefer the embellished songs.
Zebra finch males go into concert mode too, mostly speeding up the song and keeping the pitch under tight control. “It’s subtle,” says Woolley.
To see if female finches reacted to differences barely perceptible to humans, Woolley broadcast the concert version through one speaker and the singing-in-the-shower version through a different speaker for five song pairs. Females between the speakers sidled back and forth and then typically perched beside the concert version. The response was strongest when a female heard her mate’s concert song. Females without a mate also preferred the concert version, even when they had never encountered the singer.
Researchers also tracked reactions in the female brains after exposure to one version of the song or the other. An increased number of cells that produce the ZENK protein showed that the caudomedial mesopallium, a brain region associated with social processing, responded to the concert version.
The study sheds light on what the female listener gleans from the birdsong, says Steve Nowicki, a behavioral ecologist at Duke University in Durham, N.C. “We know almost nothing about the female side of the story,” he says.
The findings also caught the attention of Duke’s Erich Jarvis, who first reported extra activity in part of the male zebra finch brain when singing their concerts. “The biggest story to me is that there’s a lot more meaning in these songs than people had thought,” he says.