The present study evaluated Se bioaccumulation in four waterbird species (n=206 birds) that breed within San Francisco Bay, California, U.S.A.: American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), Forster's terns (Sterna forsteri), and Caspian terns (Hydroprogne caspia). Selenium concentrations were variable and influenced by several factors, including species...