Contaminants in eggs of western snowy plovers and California least terns: is there a link to population decline?

Environmental contaminants may have adverse effects on avian reproduction and may be contributing to declines of avian species nesting along the southern California Coast. Examples of impaired reproduction caused by organochlorine pesticides, PCBs, and elements such as mercury (Hg) and selenium (Se) include delayed ovulation, reduced egg production, defective eggshells, decreased hatchability, embryotoxicosis, aberrant incubation behavior, and mortality of chicks and adults (Heinz 1976; Blus 1982; Ohlendorf et al. 1986).