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An adult male zebra finch (center) perches between his mate (left) and his son (right).

Michael Goldstein

Teen zebra finches seek moms’ approval for their new tunes

It’s hard to imagine a teen asking their mother for approval on anything. But a new study shows that male zebra finches—colorful songbirds with complex songs—learn their father’s tune better when mom “fluffs up” to signal her approval. This is the first time the songbirds, thought to be mere memorization machines, have been shown to use social cues for learning—putting them in an elite club that includes cowbirds, marmosets, and humans. The finding suggests other songbirds might also learn their tunes this way, and that zebra finches are better models for studying language development than thought.

“Female zebra finches play an important role in male learning, in some ways even rivaling that of the male tutors,” says Karl Berg, an avian ecologist at the University of Texas in Brownsville, who was not involved in the new study. Previously, scientists knew only that the nonsinging females played some role in song acquisition, because males raised with deaf females develop incorrect songs.

Researchers have long known that female brown-headed cowbirds make quick, lateral wing strokes to approve the songs of juvenile males (as in finches, only male cowbirds learn to sing). Most scientists discounted the cowbirds’ social cues as an isolated oddity, because the birds are brood parasites. But cowbirds’ similarities to zebra finches—both are highly social and use their songs to attract mates rather than claim territories—led Cornell University developmental psychobiologists Samantha Carouso-Peck and Michael Goldstein to wonder whether female finches also use social cues to help young males learn the best, mate-attracting songs.

The young male learns his father’s song in part by watching his mother for cues that signal he’s singing it right.

Michael Goldstein

It takes a typical zebra finch 55 days to learn dad’s rhythmic, beeping tune. Carouso-Peck and Goldstein selected nine pairs of zebra finch brothers that were raised by their parents until they were 35 days old and just starting to practice their fathers’ songs. For 1 hour daily over 25 days, each brother sang by himself in a sound chamber equipped with a video monitor and camera. Whenever they sang, a scientist played a video of an unrelated adult female finch erecting her feathers and moving her upper body quickly from side to side; such “fluff-ups” signal that females like a male’s tune.  At the same time, the scientist played the video for the other brother, even if he wasn’t singing.

When the birds were sexually mature at 90 days old, the scientists compared the young males’ songs with those of their fathers. The birds that got female feedback in response to their singing were far more accurate than their peers, with eight of nine belting out melodies more acoustically similar to those of their fathers. “We’ve shown that a young male zebra finch isn’t learning his song via a special imitation box in his head,” Goldstein says. “He’s learning it from his mom, who loves his dad’s song and is already excited and aroused by that song.”

Such active learning closely resembles how human infants learn speech, the scientists note, making these finches even better models for studying language acquisition across species. For a young male finch, mom’s approval means he’ll likely be successful at his chief job in life: attracting a mate and reproducing.