Abstract:
Lead poisoning in California Condors (Gymnogyps californianus) was first documented in the 1980s and continues to be a major threat to the recovery of the species. We collected 126 independent blood samples from 33 free-flying individuals in Big Sur, Monterey County, California, between 1998 and 2006. Thirty-three samples (26.2%) were above background (>20 pg/dl), four (3.2%) were clinically affected (60-99 pgldl), and two (1.6%) were indicative of acute toxicity (2100 &dl). Twenty-one individuals (64%) were exposed at least once and nine (27%) were exposed on two or more occasions. We found significant differences among calendar years, the number of years condors were in the wild, and month. Most notably, we found the months of September and October to be significantly higher than any other times of year, most likely due to condors feeding on hunter-killed deer during the fall deer-hunting season. One condor from the Big Sur population died due to lead poisoning in southern California and two additional birds were treated for acute poisoning to prevent mortality. We also found that blood-lead levels increased significantly after one year in the wild. The threat of lead exposure in Big Sur appears to be less severe than in Arizona and southern California. Nonetheless all condors in the wild are at risk of lead poisoning.
Citation:
Sorensen, K. and J. Burnett. 2007. Lead concentrations in the blood of Big Sur California Condors . Unpub. Ventana Wildlife Society, 19045 Portola Dr. Ste F-1, Salinas, CA.
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