Environmental toxins can move through
the food chain with surprising speed, James Larison, an Oregon
State University biologist, found after studying white-tailed
ptarmigans in a 10,000-acre area in central Colorado. Forty-six
percent of the birds had accumulated toxic levels of the trace
metal cadmium in their kidneys.
The sequence,
Larison found, begins with willows, an important winter forage for
ptarmigans. Willows take up the metal through their roots and
concentrate it in their branches and leaves, which are then eaten
by birds and other animals.
Larison says the
study’s most important conclusion is that cadmium isn’t just
transported by water. “No one has ever anticipated these toxins
moving through terrestrial ecosystems with such ease,” he says.
Though Larison conducted his study in central Colorado’s “ore
belt,” where mining over the last century has left cadmium in
ecosystems, he says the metal can harm wildlife even without human
activity.
The Environmental Protection Agency
joined the OSU researchers this summer, and Larison says the agency
plans to invest more money in these issues in coming
years.
The study is available in the July 13
issue of Nature, or at
www.nature.com.
This article appeared in the print edition of the magazine with the headline Toxic bird feed.
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