Risk Assessment of Lead Poisoning in Raptors Caused by Recreational Shooting of Prairie Dogs

Authors

  • Robert M. Stephens U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department 3166, 1000 East University Avenue, Laramie, WY 82071
  • Aran S. Johnson U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department 3166, 1000 East University Avenue, Laramie, WY 82071
  • Regan E. Plumb U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department 3166, 1000 East University Avenue, Laramie, WY 82071
  • Kimberly Dickerson USDI Fish and Wildlife Service, 5353 Yellowstone Road, Suite 308A, Cheyenne, Wyoming 82009
  • Mark C. Mckinstry U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department 3166, 1000 East University Avenue, Laramie, WY 82071

Keywords:

blood, ferruginous hawk, golden eagle, lead, prairie dog, shooting, toxicity

Abstract

Raptors that scavenge animals containing lead (Pb) bullet fragments are subject to Pb poisoning. We analyzed nestlings tissue for signs of PB poisoning in resident ferruginous hawk (Buteo regalis) and golden eagle (Aquila chrysaetos) populations near eight black-tailed prairie dog (Cynomys ludovicianus) colonies in Thunder Basin National Grassland (TBNG), Wyoming, to determine if recreational prairie dog shooting resulted in lead poisoning in these two raptor species. For a control, we collected tissue samples from ferruginous hawks at a reference site near Rawlins, Wyoming, where shooting did not occur. Analytical tests included Pb concentration, aminolevulinic acid dehydratase activity, hemoglobin levels, protoporphyrin levels, and packed cell volume in blood samples, and Pb content in feathers. We also recovered prairie dog carcasses to determine the amount and composition of bullet fragments. We did not detect Pb poisoning in nestling raptors at any of our sites. We did, however, detect bullet fragments in 40 percent ( 4/10) of prairie dog carcasses with a mean ± SD weight of92.5 ± 60.7 mg/carcass (n = 4, Range = 10- 146 mg/carcass). Our results suggested that analysis offeathers for clinical signs of Pb poisoning might be an unreliable technique. Even though we did not detect Pb poisoning, presence of Pb bullet fragments in prairie dog carcasses indicated that recreational shooting could cause Pb poisoning if raptors scavenge on those carcasses.

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Published

2007-12-31

Issue

Vol. 13 No. 4 December (2007)

Section

Independent Refereed Articles