Friday, June 12,
2009
Elizabeth Derryberry, post-doctoral researcher at the LSU Museum of
Natural Science, has found a link between alterations in bird songs
and the rapid change in the surrounding habitat. Her research will
be featured in the July 2009 issue of the American
Naturalist.
Derryberry, a behavioral ecologist, has studied this phenomenon
since her time as a graduate student at Duke University, where she
discovered tapes from ornithologist Luis Baptista. On these tapes,
which had been recorded in the 1970s, she quickly noticed that 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.
Using aerial photographs to map the vegetation and habitat changes
that took place between 1970 and 2005, when she began the research,
Derryberry was able to determine that in places where plant growth
had increased, bird songs were slowing down.
"This is likely due to the birds' avoidance of sound
reverberation," said Derryberry. "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."
While California has experienced a re-greening of sorts, many South
American countries, many of which are important habitats for rare
and endangered species of birds, are experiencing severe
deforestation. Derryberry is now studying the effects habitat on
song in species in South America, where widespread habitat
destruction and global climate change may affect song
evolution.
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Louisiana State University
Thanks to Louisiana State
University for this article.
