Eagles-Smith, C. A., US Geological Survey - Davis F, Davis, USA, ceagles-smith@usgs.gov
Ackerman, J. T., US Geological Survey - Davis Field Station, Davis, USA, jackerman@usgs,gov
Takekawa, J. Y., US Geological Survey - SF Bay Estuary Field Station, Vallejo, USA, john_takekawa@usgs.gov
Adelsbach, T. L., US Fish and Wildlife Service, Sacramento, USA, terry_adelsbach@fws.gov

MERCURY RISK TO BIRDS IN THE SAN FRANCISCO BAY ESTUARY

The San Francisco Estuary is a site of hemispheric importance for waterbirds, and also has a legacy of mercury contamination. We examined space use in four common waterbird species and assessed mercury concentrations in adults, chicks, eggs, and their prey, and quantified the effects of mercury on reproduction. We found that mercury was highest in Forster’s terns, followed by stilts, Caspian terns, and avocets. Overall, we estimated that risk to reproductive impairment was 27%, 22%, 10%, and 1% in Forster’s terns, stilts, Caspian terns, and avocets. Moreover, 58% and 46% of breeding Forster’s terns and their eggs respectively, were at high risk to mercury impairment. Failed to hatch and abandoned eggs had more mercury than randomly collected eggs for Forster’s terns but not stilts or avocets. Further, we found that hatching success declined with increasing egg mercury in Forster’s terns but not stilts or avocets. We also found that dead stilt (but not avocet) chicks had higher down mercury concentrations than randomly sampled living chicks. Our results indicate that waterbird exposure to mercury is high enough to be a cause of concern, and that reproduction may be impaired.

Oral presentation

Presentation is given by student: No
Session #:187
Date: 03-07-2008
Time: 09:15