Birds' songs change over time

From NewScientist.com:

JUST as the Bee Gees' disco style sounds antique compared to hip-hop, birdsong can also go out of fashion. Such stylistic changes may help explain how mating barriers arise, eventually leading to new species.

Behavioural ecologists have long known that some songbirds develop local dialects, and that individual birds respond more strongly to their own dialect than to a foreign one. Less is known about how, or how quickly, such differences arise.

To study how a dialect changes over time, Elizabeth Derryberry, a behavioural ecologist at Duke University in Durham, North Carolina, compared recordings of male white-crowned sparrows' song from 1979 - when the Bee Gees topped the charts - and 2003. The modern song, she found, was slower and lower in pitch.

Derryberry received a research award in 2004 from the American Ornithologists' Union for "The impact of culture and selection on vocal performance: implications for song evolution."

Ilustration courtesy of WhatBird.com