Blood-lead Levels of Fall Migrant Golden Eagles in West-central Montana

EXTENDED ABSTRACT.—Lead has long been documented as a serious environmental hazard to eagles and other predatory and scavenging avian species (Redig et al. 1984, Kramer and Redig 1997). The use of lead shotgun pellets for waterfowl hunting on federal and state lands was banned in 1991 due to lead poisoning in Bald Eagles (Haliaeetus leucocephalus), Golden Eagles (Aquila chrysaetos) and numerous waterfowl species. Spring migrating eagles sampled in west-central Montana between 1983 and 1985 showed elevated blood-lead levels in 85% of 86 Golden Eagles and 97% of 37 Bald Eagles (Harmata and Restani 1995). The authors suggested shot from waterfowl hunting and fragmented lead-core rifle bullets in ground squirrels (Spermophilus spp.) as a possible lead source. More recently, lead poisoning from spent ammunition has been identified as the leading cause of death in California Condors (Gymnogyps californianus), prompting the recent ban of lead ammunition within the “California Condor Recovery Zone” (Hunt et al. 2006, Cade 2007). Another study on Common Ravens (Corvus corax) in Wyoming has shown a direct correlation between elevated bloodlead levels and the onset of rifle hunting season (Craighead and Bedrosian pers. comm.)