In another part of the study, the researchers showed that feathers can be used to monitor lead exposure in condors. They analyzed lead in tissue samples and a feather from a condor that had died of lead poisoning in Arizona. They found that the feather, sampled sequentially along its length, provided a record of the bird's history of lead exposure.
"This shows that we can use feathers to look at the history of lead exposure in individual condors, and we're just starting to do that now with birds that have been reintroduced in California," Smith said.
The elevated lead levels in reintroduced condors are cause for concern even when they are below the level that would cause death from acute lead poisoning, he added. Although it is very difficult to evaluate sublethal effects of toxic substances in wild animals, he said, lead is well known to cause neurological problems in vertebrate animals at relatively low levels of exposure.
"The lead levels that we commonly see in condors are well above the levels considered a concern for human health. If we saw those levels in children, they'd be diagnosed as lead-poisoned and medically treated," Smith said.
Church said she hopes the findings prompt greater efforts not only to reduce lead exposure in condors but to reduce lead contamination in California in general.
"Lead is a well-known toxin that should no longer be getting into the environment, and it would truly be a shame if lead poisoning negated the significant condor conservation efforts and achievements that have taken place over the past several decades," she said.
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Contact: Tim Stephens
stephens@ucsc.edu
831-459-4352
University of California - Santa Cruz
30-Aug-2006