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"Long
before it's in the papers"
April 29, 2009
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Pollution may make birds change their tune
Feb. 28, 2008
Courtesy Public Library of Science
and World Science staff
Nothing like a bird
chirping in the morning to remind you of nature’s glory, right? The European starling,
Stumus vulgaris. (Courtesy Wash. Dept. of Fish & Wildlife)
Maybe not quite. A rather creepy new research finding suggests some
bird songs are a bit unnatural—influenced by pollutants,
which cause at least one species of birds to change their songs.
It’s the latest of a number of studies to
note that some of pollution’s biological effects are not only unhealthy, but bizarre. Studies have found contaminants causing
sex
changes, for example, or even possibly raising suicide
and child abuse rates.
In the bird study, interestingly,
researchers found that the revised, more elaborate tunes were appealing
to female birds. But the affected birds also suffered weak immune
systems, the investigators said.
The scientists studied male European starlings, Stumus vulgaris, feeding on earthworms at a sewage treatment works in the southwest U.K. Many of the worms were
found to be contaminated with chemicals similar to estrogen, a hormone
involved in the development of sexual characteristics.
Affected male birds showed marked changes in brain and behaviour,
including more complex songs, which females preferred, the researchers said. And a brain area responsible for song complexity, called the high vocal centre, was also found to be enlarged in
the males.
This region is particularly sensitive to estrogen, which is known to cause “masculinisation” of the songbird brain, according to the research team. The study, by Katherine Buchanan of Cardiff University in the
U.K. and colleagues, appeared Feb. 27 in the research journal
PLoS One.
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