"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."