USING FEATHERS TO ASSESS RISK OF MERCURY AND SELENIUM TO BALD EAGLE REPRODUCTION IN THE GREAT-LAKES REGION

Mercury (Hg) and selenium (Se) concentrations were determined in feath ers of nestling and adult bald eagles (Haliaeetus leucocephalus) in th e Great Lakes region, 1985-1989. Relationships between concentrations and two measures of reproduction, productivity and nesting success, we re examined. Hg and Se were detected in all feathers analyzed. A maxim um concentration of 66 mg/kg Hg was found in adult feathers in the upp er peninsula of Michigan. The geometric means of Hg in adult feathers for sample areas were: interior lower peninsula of Michigan, 21 mg/kg; interior upper peninsula of Michigan, 21 mg/kg; Lake Superior, 22 mg/ kg; Lakes Michigan and Huron, 20 mg/kg; and Lake Erie, 13 mg/kg. The g eometric means of Hg in nestling feathers for sample areas were: inter ior lower peninsula of Michigan, 8.8 mg/kg; interior upper peninsula o f Michigan, 8.1 mg/kg; Lake Superior, 8.7 mg/kg; Lakes Michigan and Hu ron, 8.0 mg/kg; Lake Erie, 3.7 mg/kg; and Voyageurs National Park, 20 mg/kg. Se concentrations were not significantly different across regio ns or between adult and nestling feathers, and Se concentrations range d from 0.8 to 3.2 mg/kg. No significant relationships between adult or nestling feather concentrations and either measure of reproduction, p roductivity or nesting success, was found for either Hg or Se. It was concluded that neither Hg nor Se concentrations are currently affectin g bald eagle reproduction in the Great Lakes region.