Lead is commonly ingested by wild raptors and other avian scavengers through feeding on carcasses of animals shot with lead bullets. In 2013 the California legislature passed a law (AB711) banning lead bullets used for hunting by 2019. Exposure to lead has been identified as the primary source of mortality in the endangered California condor (Gymnogyps californianus). Raptors such as bald eagles (Haliaeetus leucocephalus), golden eagles (Aquila chrysaetos), and various hawks also ingest lead by scavenging, as well as turkey vultures (Cathartes aura), common ravens (Corvus corax), and American crows (Corvus brachyrhynchos). Sub-lethal concentrations of lead in their bodies can affect their neurological systems, altering vision and coordination needed to avoid danger and to hunt.
IWS is planning on examining lead concentrations in select avian scavengers in California for three years before, and at least three years after, the lead ammunition ban. The goal of the investigation will be to determine if the lead ammunition ban results in any change in the availability of lead to these scavengers. Birds will be trapped at several sites throughout California, at which time we will collect a blood sample to test lead concentrations. With this information we hope to evaluate how changes in available lead may affect California condor conservation efforts and the welfare of other scavenging birds.
Background photo - Lori Iverson / USFWS, CC license, cropped