Sparrows' love tunes change with the landscape

Washington, May 21 (ANI): A new study from Duke University has found that changes in habitat have a significant impact on the way birds sing.

Lead researcher and biologist Elizabeth Derryberry found that male white-crowned sparrows have lowered their pitch and slowed down their singing so that their love songs would carry better through heavier foliage.

"This is the first time that anyone has shown that bird songs can shift with rapid changes in habitat," she said.

During the study, Derryberry compared the recordings of individual birds in 15 different areas with some nearly forgotten recordings made at the same spots in the 1970s by a California Academy of Sciences researcher.

She found that the musical pitch and speed of the trill portion of the sparrows' short songs had dropped considerably.

Further analysis showed that one population whose song hadn't slowed down lived in an area where the foliage hadn't changed either.

Derryberry believes that slower song suffers less reverberation in denser foliage and will be heard more accurately.

That means it is more likely to be copied by young males who are choosing which song they will learn.

Over generations, that should cause the song to slow down and drop in pitch as the foliage changes.

However it is still unclear whether the clearer song wins better territories or mates, although she does know that these changes in song do affect both male and female behaviour.

She had earlier discovered that female white-crowned sparrows preferred the slower new songs to the chirpy old ones.

"Given how much the world's habitats are changing, this is sort of an unexpected but useful factor to monitor," Derryberry said. (ANI)