Contaminant Exposure of Bald Eagles via Prey at Voyageurs National Park, Minnesota, 1993
Giovengo K and U.S. Fish and Wildlife Service. 1997. Contaminant Exposure of Bald Eagles via Prey at Voyageurs National Park, Minnesota, 1993. Completion Report. Project ID #93-1261-3F13. U.S. Fish and Wildlife Service. Bloomington, MN
Despite the increase in numbers and progress toward recovery in Minnesota from DDE years, the bald eagle population at Voyageurs National Park has lagged behind the recovery rate of other eagle populations. Recent studies have shown that bald eagles in Voyageurs National Park contain elevated concentrations of certain pesticides and industrial contaminants. Elevated concentrations of polychlorinated biphenyls (PCBs), dichloro diphenyl dichloroethylene (DDE), and mercury and other compounds in the prey base may be contributing to the reduced reproductive success in Voyageur's eagle population. In order to assess the potential route and degree of contaminant exposure of bald eagles at Voyageurs National Park and the relationship of that exposure to reproductive performance, we obtained eaglet plasma and feathers and known prey items (fish and bird) from selected sites in Voyageurs National Park and adjacent exterior sites during the 1993 breeding season for organochlorine and mercury analysis. Eaglet mercury concentrations, but not total PCBs or DDE, differed among the four major lakes within Voyageurs National Park. However, no significant correlations between eaglet tissue and mean five-year productivity for total PCBs, DDE, or total mercury were observed. Total PCBs and organochlorine pesticides were found in significantly higher concentrations in herring gulls than the fish species obtained throughout the park. Mercury concentrations, on the other hand, were found in high concentrations among all of the four species measured. Mercury concentrations, but not total PCBs or organochlorine pesticides, in Voyageurs National Park prey were equal to fish concentrations determined to have the potential to cause adverse effects on bald eagles in the Great Lakes.
- Type
- Published Report
- Authors
- Giovengo, Keren Ensor; U.S. Fish and Wildlife Service
- Date of Issue
- 1997-08
- Publisher
- U.S. Fish and Wildlife Service
- Units
- VOYA
- Keywords
- Bald Eagle (Haliaeetus leucocephalus), Contaminant, dichloro diphenyl dichloroethylene (DDE), Mercury (Hg), Minnesota, Monitoring, Organochlorine, Pesticides, polychlorinated biphenyls (PCB), Population, prey base, Voyageurs National Park