Contaminant assessment of coastal bald eagles at Maine Coastal Islands National Wildlife Refuge and Acadia National Park

Mierzykowski, Steven; Welch, Linda; Todd, Charles; Connery, Bruce; DeSorbo, Christopher

From Official Executive Summary: “Environmental contaminants including organochlorine compounds (e.g., polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE)), polybrominated diphenyl ether (PBDE), and mercury were measured in 16 non‐viable or abandoned bald eagle Haliaeetus leucocephalus eggs and 65 nestling blood samples collected between 2000 and 2012 from the Maine coast. The study objectives were to compare current contaminant levels in eggs and blood to suggested toxicity threshold levels reported in the scientific literature and to two previous Maine bald eagle investigations conducted in the 1990s. The study produced the following results: • Current levels of organochlorine compounds, specifically PCBs and p,p’‐DDE, in coastal Maine bald eagles eggs and plasma are significantly lower (p < 0.05) than results reported in earlier Maine collections and lower than suggested toxicity effect thresholds. • Compared to other bald eagle studies in North America, PCBs in coastal Maine bald eagle nestling plasma are on the higher end of reported concentrations ranges. • PCBs in bald eagle nestling plasma collected from three areas along the Maine coast ‐ the Sheepscot River estuary, Frenchman Bay, and Little Machias Bay – are elevated and warrant further investigation. Eggs from two nest territories located near Acadia National Park did not show decreases in PCB concentrations from earlier collections and also warrant further investigation. • PBDE levels in coastal Maine bald eagle eggs do not appear elevated compared to a suggested toxicity threshold for another raptor species, the American kestrel. • PBDE levels in coastal Maine bald eagle nestling plasma do not appear elevated compared to other bald eagle collections in North America, but toxicity thresholds for PBDE in bald eagle plasma have not been published and the significance of the detected levels is not known. • Mercury levels in coastal Maine bald eagle eggs (p = 0.197) and nestling whole blood (p= 0.335) do not show any significant changes from earlier collections. Current levels of mercury in bald eagles along the Maine coast are not elevated compared to suggested egg toxicity effect thresholds or to whole blood exposure scales.“

Contaminant assessment of coastal bald eagles at Maine Coastal Islands National Wildlife Refuge and Acadia National Park

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