By Jennifer Viegas
It goes a little something like this: A young male zebra finch, whose father taught him a song, shared that song with a brother, with the two youngsters then creating new tunes based on dad’s signature sound.
The musical bird family, described in the latest Biology Letters, strengthens evidence that imitation between siblings and similar-aged youngsters facilitates vocal learning. The theory could help to explain why families with multiple same sex siblings, such as the Bee Gees and the Jackson 5, often form such successful musical groups.
Co-author Sébastien Derégnaucourt told Discovery News that, among humans, “infants have a visual preference for peers of the same age, which may facilitate imitation.” He added that it’s also “known that children can have an impact on each other’s language acquisition, such as in the case of the emergence of creole languages, whether spoken or signed, among children exposed to pidgin (a grammatically simplified form of a language).”
Pidgin in this case is more like pigeon, since the study focused on birds. Derégnaucourt, an associate professor at University Paris West, collaborated with Manfred Gahr of the Max Planck Institute for Ornithology. The two researchers studied how the young male zebra finch from a bird colony in Germany learned from his avian dad.
“Young male zebra finches learn to sing during a sensitive period that starts around day 25 post-hatch,” he said. “A phase of intense practice, which recalls human’s babbling phase, lasts for a couple of months. During this time, the young bird is comparing its own vocal output with a song model that he memorizes. The song model is usually its father’s song.”
Derégnaucourt went on to explain that young male zebra finches -- when they reach 30 to 35 days -- practice on their own, based on memory, since dad likely has literally flown the coop by then.
“Around 90 to 100 days post hatching, song structure stabilizes and no significant changes will occur during the remainder of the bird’s life,” he said.
The researchers housed the young male bird with one of his brothers. That second male -- after hearing his brother sing and frequently joining in -- learned dad’s tune. Both birds then came up with their own unique versions, which sounded a lot like that of their father, but with some different notes and syllables.
The tunes are love songs, since they are “used in courtship context,” according to Derégnaucourt. He said the songs might also be used “as kin and group signature,” but not in very antagonistic situations, since these birds do not defend territories.
While sibling rivalries are all too common among birds, humans and other animals, there’s a definite benefit to having a brother or sister around, particularly when parents are absent.
Derégnaucourt explained that when dad isn’t available, as often happens in the big bird-eat-little bird world, young finches can then learn from each other.
That's no small effort for this particular species, whose vocal repertoire comprises about 10 different calls. Females produce calls too, but they do not sing.
Ofer Tchernichovski, a professor of psychology at Hunter College, told Discovery news that, prior to this new study, “The role of siblings in vocal learning, both in humans and in song birds, was not studied much. The current results demonstrate, at least in songbirds, that birds can tutor each other very efficiently, so as to allow rapid propagation of vocal culture horizontally (meaning among peers). These results are very exciting, and will surely lead to additional discoveries.”
He added, “Cumulative vocal culture is shared across songbirds and humans, and the capacity to rapidly propagate vocal culture horizontally is highly significant.”