Anyone who has spent time around a child knows that youngsters often seek parental approval in some fashion. "What do you think of my drawing?" or "Hey, listen to this noise I can make!"
It turns out that human children aren't the only ones who turn to their parents when they want that gold star. Teen zebra finches turn to their moms when crafting new songs, studying them for a reaction, according to a study published in Current Biology.
This is the first time researchers have noticed that the songbirds look for tiny social cues when learning songs instead of relying on rote memorization, something they have in commons with humans.
Something to sing about
Most of the scientific work regarding how some songbirds learn their tunes boils down to younger birds memorizing and then refining songs they hear from older songbirds. Sparrows are a classic example of this sort of behavior. And, for a long while, so were zebra finches.
These finches are loud singers that really enjoy belting out their tunes. Males all have different songs, but males from the same family tend to have some similarities in their notes. Finches also learn best from an in-person tutor, almost always another male. They can still pick up songs without a guide present, but the songs are learned more quickly when another male is present and teaching them. Without a tutor, some finches will develop songs that are "not normal," according to the researchers behind the Current Biology study, Michael Goldstein, who is an associate professor of psychology at Cornell University, and Samantha Carouso-Peck, doctoral candidate.
There may be more to the process, however, than just a helpful male. Goldstein and Carouso-Peck wanted to know more about how social learning might play a role in the finches' song development, with a specific emphasis on the presence of females. Past studies had demonstrated that males learning songs around deaf females "develop more atypical songs" and that blindfolded males learn songs more accurately when raised with a female sibling. In short, females perform some function in how males learn their songs.
The clue, Goldstein and Carouso-Peck thought, might be in how birds see the world, specifically their ability to see things that happen too fast for the human eye to perceive. This ability hasn't factored into a lot of studies, and so the two researchers recorded females while males learned songs. What they found, once the video was slowed down, was that female zebra finches "encourage" their sons by fluffing up their feathers in something similar to an arousal behavior. You can see the fluffing in the video below, provided by Cornell University.
"Over time, the female guides the baby's song toward her favorite version. There's nothing imitative about it," Carouso-Peck said in a statement.
To test this, Goldstein and Carouso-Peck took nine pairs of zebra finches, all of them genetic brothers raised by their parents for a little over a month. When the males began to develop a practice song, the researchers split the birds into two different groups. One set would see a playback of their mother fluffing up when they sang in a way that matched their father's song. The other set would see the same fluff up at the same time as their brother, regardless of which bird was singing.
Once the songs were finalized, the duo of researchers compared the different groups' songs to that of their fathers. Birds that would see their mother fluff her feathers while they practiced had more accurate songs than those that saw the fluffing only at random times. Had the previous way of thinking been correct — that the birds learn through memorization and no other cues — then both groups would have developed accurate songs, the researchers reasoned.
One reason for the need for female approval may be that finches use their songs to attract mates rather than declare and defend territory. Mom's OK on a song may let the budding songbirds know that they're on the right path.
Goldstein and Carouso-Peck say this fresh insight into zebra finch behavior may help us when it comes to translating zebra finch vocal learning to humans. The finches are used in research of vocal learning and production as well as research on Parkinson's disease, autism, stuttering and genetic disorders of speech. Increasing our understanding of how the finches learn may help us understand how humans acquire speech.