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

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)816-823
Number of pages8
JournalJournal of wildlife diseases
Issue number4
StatePublished - Oct 2017

Bibliographical note

Funding Information:
We thank staff at Eagle Valley and The Raptor Center at the University of Minnesota for supporting field and laboratory work, the Wisconsin and Iowa Departments of Natural Resources, the Wisconsin State Climatology Office, and many public and private individuals who supported this effort with their time and expertise. We thank Dave Staples, Minnesota Department of Natural Resources fisheries research biometrician, for statistical consultation services. We thank the Research Services Council from the University of Nebraska at Kearney for the grant awarded to R.A.L., which funded blood lead level analysis.

Publisher Copyright:
© Wildlife Disease Association 2017.

Copyright 2017 Elsevier B.V., All rights reserved.


  • Ammunition
  • Bald eagle
  • Blood
  • Haliaeetus leucocephalus
  • Hunting
  • Lead
  • Mississippi river
  • Snowfall


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