Blood-Lead Levels Of Fall Migrant Golden Eagles In West- Central Montana

Abstract

Lead has long been documented as a serious environmental hazard to eagles and other predatory, opportunistic and scavenging avian species. 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. At that time, this was thought to be the only major source of the lead exposure. More recently, lead poisoning from ingested lead-bullet fragments and shotgun pellets has been identified as the leading cause of death in California Condors (Gymnogyps californianus), leading to the recent ban of lead ammunition within the “California Condor Recovery Zone.” Another on-going study on Common Ravens (Corvus corax) and Bald Eagles in Wyoming has shown a direct correlation between very high blood-lead levels and the on-set of rifle hunting season. Indeed, there is overwhelming evidence showing that lead toxicity is still prevalent in the environment and mounting data points to fragmented rifle bullets as the source. We sampled blood from 131 Golden Eagles captured on migration during the fall from 2006 and 2010 to quantify a suite of possible heavy metal contaminants, with an emphasis on lead.