Why birds change their tune

[n2doc]

A species of ground finch (Geospiza fortis) on Daphne Major in the Galapagos Islands appears to have sped up the trill of its tune to differentiate itself from a similar species that colonized the island in 1983, researchers say.
Alan Boyle writes: More than a dozen species of birds in the Galapagos Islands served as prime experimental subjects for Charles Darwin's ideas about evolution -- and today, "Darwin's finches" still provide examples of evolution at work. The latest example, revealed today, suggests that the songbirds modify their tunes to distinguish themselves from similar species.
The finches in question are Geospiza fortis (medium ground finch) and G. scandens (cactus ground finch), longtime residents of Daphne Major Island in the Galapagos chain. The males of each species have a song that's characteristic enough to ensure that the females of the species respond to the right mating call. There might be individual variations that crop up as each father teaches his sons to sing -- but the features of the song, such as the trill and the tempo, has generally stayed close to the norm.
Until 1983, that is.
That's when another species, the large ground finch (G. magnirostris), moved onto Daphne Major and began growing in numbers. This third species had songs that were somewhat similar to that of the other two species. But as time went on, G. fortis and G. scandens changed their typical songs: The trills became faster, while the duration of notes and the inverval between them became shorter.

http://cosmiclog.msnbc.msn.com/_news/2010/11/01/5389939-why-birds-change-their-tune

[Vincardog]

1. Evolution and life goes on

[Jim__]

2. I wonder if that variant of the tune was always present among some of the males ...

... and became dominant because of its difference from the tune of the other species; or do the males have variances of their tunes and use the one that is most successful, or ...

[Igel]

3. A lot of birdsong is taught.

Zebra finch males, for instance, grow up with no viable song if they're raised without an adult male to teach them.

In Los Angeles we had some bird that nested near our bedroom window that had the most common kind of car alarm "learned" as its song--police siren, ambulance, horn. . . Cute the first hundred times we heard it, a bit annoying after that.

The idea of some sort of musical phenotypic variation is intriguing. Might do a search to see if it's been studied.