Alterations in bird songs linked to habitat change

Washington, June 13 (ANI): An American study has found a link between alterations in bird songs and the rapid change in the surrounding habitat.

Elizabeth Derryberry, a behavioural ecologist and post-doctoral researcher at the LSU Museum of Natural Science, says that she has studied this phenomenon since her time as a graduate student at Duke University, where she discovered tapes from ornithologist Luis Baptista.

On the tapes recorded in the 1970s, she said, the birds were singing quite a different tune than those happening right outside her door.

"I was really surprised to find that songs had changed in a similar way in so many different populations," said Derryberry.

She used aerial photographs to map the vegetation and habitat changes that took place between 1970 and 2005.

The researcher found that bird songs were slowing down in places where plant growth had increased.

"This is likely due to the birds' avoidance of sound reverberation. Because California has steadily increased vegetation in areas that had previously been cleared, the birds slowed the frequency and tempo of their songs in order to avoid reverberation distorting their mating song," said Derryberry.

She is presently studying the effects of habitat on song in species in South America, where widespread habitat destruction and global climate change may affect song evolution.

The study is scheduled for publication in the July 2009 issue of the American Naturalist. (ANI)