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(P855) Assessing Risks to Resident Bald Eagles in the Kalamazoo River Floodplain: The Exposure Assessment.
Strause, Karl*,1, Zwiernik, Matthew1, Blankenship, Alan, Villeneuve, Daniel1, Park, Cyrus1, Bradley, Patrick1, Pastva, Stephanie1, MacCarroll, Monica1, Neigh, Arianne1, Moseley, Pamela1, 1 Michigan State University, E. Lansing, MI, USA
ABSTRACT- The Baseline Ecological Risk Assessment (BERA) for the Kalamazoo River site predicts elevated risks to resident bald eagle populations from dietary exposure to PCBs. To verify modeled exposures to resident bald eagle populations at the site and to discern site-related PCB exposures from background exposures associated with a regional Great Lakes forage base, site-specific exposures to resident eaglesa are derived from a three-year study (2000-2002) of foraging activity and success at three discrete locations (n = 2 nests at each location) in the Michigan lower peninsula. Two methods are employed to characterize diet composition at each nest. Prey items are identified through direct observation (2000+ hours) of prey delivery and nestling feeding activities at each nest site during the brooding/nestling phase of the reproductive cycle. Prey remains are also collected from the active nest and base of the nest tree for subsequent forensic analysis to determine class and species. Prey remains are collected twice during each field season, at nestling banding and subsequent to nestling departure from the nest (post-fledge nest climb). Additional observations of resident eagle foraging activities at the Kalamazoo River Site provide for refinement of the site use factor and delineation of foraging habitat boundaries. Diet composition was found to be similar at each of the three study sites, although site-specific diet composition was found to vary by and within class (species preferences) from proportions used in the BERA. Principal prey species identified through these diet studies are collected and analyzed to determine PCB concentrations in eagle forage and to estimate a potential average daily dose through ingestion of contaminated prey. Congener-specific PCB analyses of prey and nestling blood samples is also used to identify the proportion of PCB body-burden potentially ascribed to a Lake Michigan derived forage base.
Key words: PCBs, Bald Eagle, Ecological Exposure Assessment, Superfund
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