Three new scientific studies by University of California researchers confirm that lead poisoning of endangered California condors and other wildlife is due to scavenging animals ingesting fragments of spent lead hunting ammunition. One study also demonstrated that the 2008 California ban on lead ammunition in condor habitat has been effective in removing lead from the environment, as evidenced by a significant reduction in lead exposure in golden eagles and turkey vultures soon after the new regulation took effect.
"This research adds to the mountain of scientific evidence about the dangers of lead in the wild and provides important confirmation that banning lead in hunting ammunition can have positive, tangible effects for wildlife," said Jeff Miller, conservation advocate with the Center for Biological Diversity, which has been pushing for a national ban on lead hunting ammunition and lead fishing tackle. "The dangers of lead in the wild are more apparent than ever and, given that there are already safe and available nontoxic alternatives for hunters and anglers, there's no reason to perpetuate the continued lead poisoning of wildlife."
Researchers from U.C. Santa Cruz confirmed that lead ammunition is the principal source of lead exposure for poisoned California condors. The researchers analyzed lead isotopes in blood samples from pre-release and free-flying condors in California and compared them with a representative selection of 71 different lead-based ammunition samples, most collected in the field. The lead isotopic signature in free-flying condors, which can scavenge on carcasses tainted with lead ammunition fragments, differs from that in pre-release birds. About 90 percent of blood samples from free-flying condors had an isotopic composition best explained by exposure to lead-based ammunition.
The research also demonstrates that lead exposure causes chronic, long-term health effects in condors as well as acute poisonings. Nearly all 100 free-flying condors in California have suffered from severe lead poisoning at least once, and 35 percent of condor blood samples from 2004 to 2009 showed high blood lead levels indicating chronic exposure to potentially lethal lead levels. Lead-poisoned condors must routinely be removed from the wild and subjected to stressful chelation treatment to save their lives. One-third of wild condors are suffering from chronic lead poisoning at levels that cause toxicological effects and sublethal impacts.
One study, the first of its kind, found that blood lead levels in free-flying turkey vultures rose during deer hunting season and in areas with wild pig hunts.Another U.C. Davis study concluded that the 2008 lead-ammunition ban in the California condor range reduced lead exposure in golden eagles and turkey vultures in 2009.
The Center, Public Employees for Environmental Responsibility and Project Gutpile, a hunting group, filed a lawsuit against the Environmental Protection Agency last November for failing to regulate the use of toxic lead hunting ammunition and fishing gear that frequently poisons and kills eagles, swans, cranes, loons, condors and other wildlife throughout the country. The EPA denied a formal petition to ban lead in fishing tackle and hunting ammunition despite long-established science on the dangers of lead poisoning in the wild, which kills millions of birds each year and also endangers public health. Nearly 500 peer-reviewed scientific papers have been published showing lead poisoning of scavengers that eat lead ammunition fragments in carcasses, and of waterfowl that ingest spent lead shot or lost lead fishing sinkers.
The campaign to end the use of toxic lead ammunition and fishing tackle is gaining momentum. So far, 117 organizations in 30 states representing birders, conservationists, hunters, scientists, veterinarians, American Indians and public employees have joined the call for a federal ban on lead ammunition and fishing tackle to prevent wildlife poisoning and safeguard human health.
The U.C. Davis studies, Impact of the California Lead Ammunition Ban on Reducing Lead Exposure in Golden Eagles and Turkey Vulturesand Lead Exposure in Free-Flying Turkey Vultures Is Associated with Big Game Hunting in California, were funded by the California Department of Fish and Game and published by the journal PLoS ONE.The findings of the U.C. Santa Cruz study, Lead Poisoning from Ingested Ammunition is Precluding Recovery of the Endangered California Condor, were presented at the March 2011 annual Society of Toxicology meeting and are being prepared for publication.
