Lead poisoning of scavenging raptors occurs primarily via consumption of game animal carcasses containing lead, which peaks during fall firearm hunting seasons. We hypothesized that snowfall would mitigate exposure by concealing carcasses. We categorized blood lead level (BLL) for a subsample of Bald Eagles (Haliaeetus leucocephalus) from the Upper Mississippi River Valley and described BLL with respect to age, sex, and snowfall. We captured Bald Eagles overwintering in the Upper Mississippi River Valley (n=55) between December 1999 and January 2002. Individual BLL ranged from nondetectable to 335 μg/dL, with 73% of the samples testing positive for acute exposure to lead. Eagle BLL did not significantly differ between age or sex, but levels were higher immediately following the hunting season, and they were lower when the previous month's snowfall was greater than 11 cm. This study suggests a window of time between the white-tailed deer (Odocoileus virginianus) hunting season and the onset of snow when the population experienced peak exposure to lead. Combining these findings with existing research, we offer a narrative of the annual lead exposure cycle of Upper Mississippi River Valley Bald Eagles. These temporal associations are necessary considerations for accurate collection and interpretation of BLL.
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1 October 2017
INFLUENCE OF SNOWFALL ON BLOOD LEAD LEVELS OF FREE-FLYING BALD EAGLES (HALIAEETUS LEUCOCEPHALUS) IN THE UPPER MISSISSIPPI RIVER VALLEY
Ronald A. Lindblom,
Letitia M. Reichart,
Brett A. Mandernack,
Matthew Solensky,
Casey W. Schoenebeck,
Patrick T. Redig
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Journal of Wildlife Diseases
Vol. 53 • No. 4
October 2017
Vol. 53 • No. 4
October 2017
ammunition
Bald Eagle
blood
Haliaeetus leucocephalus
hunting
lead
Mississippi River