New Study: Over Two Thirds of Fatalities of Endangered California Condors Caused by Lead Poisoning

California Condor by Susan Haig
California Condor by Susan Haig

(Washington, D.C., February 8, 2012) A new study authored by San Diego Zoo Institute for Conservation Research scientists has found that 67 percent of adult condor deaths are attributable to lead poisoning.

Among the collaborators in the study were the U.S. Fish and Wildlife Service, the National Park Service, the U.S. Geological Survey, the University of California at Santa Cruz and Davis, The Peregrine Fund, The San Diego Zoo Global and the Phoenix Zoo.

There have been a total of 135 endangered California Condor deaths from October 1992 (the date of the first death of a condor released back into the wild as part of the condor recovery program) through December 2009.  A definitive cause of death was determined for 76 of the 98 condor deaths the study looked at.  Because of the condition of the carcass (and other factors that complicate definitively assigning a cause) the cause of death could not be attributed to all recovered dead condors. Lead toxicosis was the most important factor in juvenile mortality, causing 13 of 50 deaths (26 percent) and causing ten of 15 deaths in adults (67 percent). Trash ingestion was the most important mortality factor in nestlings, causing eight of 11 deaths (73 percent).

The report states that "The mortality factors thought to be important in the decline of the historic California Condor population, particularly lead poisoning, remain the most important documented mortality factors today. Without effective mitigation, these factors can be expected to have the same effects on the sustainability of the wild populations as they have in the past."

"Although lead toxicosis from spent ammunition still threatens the survival of the California Condor, one of our most iconic species, the good news is that solutions are available in the form of nontoxic ammunition.  We can make this a win-win situation if we choose to," said Dr. Bruce A. Rideout,  lead author of the study and Director, Wildlife Disease Laboratories, Institute for Conservation Research
San Diego Zoo Global.

"In all likelihood, many more condors would likely have died from lead poisoning had it not been for the fact that all wild condors in California are normally captured twice each year, tested for lead poisoning and then treated if necessary," said Darin Schroeder, Vice-President for Conservation Advocacy for American Bird Conservancy (ABC), one of the nation's leading bird conservation organizations.

The massive effort to save the California Condor was initiated in 1982 when the remaining 22 wild birds were captured in a last-ditch effort to save the species. Of the 390 condors that exist today, 210 are in the wild, with 118 in California, 73 in Arizona and 19 in Mexico.

ABC has analyzed almost 500, mostly peer-reviewed studies, and determined that the source of the vast majority of lead poisoning of birds and other wildlife is lead ammunition from hunting.  Birds either consume lead pellets when they mistake them for grit that they used to help digest their food, or when they scavenge on the remains of animals hunted with lead shot or bullets.  A single ingested lead pellet can cause a slow and agonizing death for many birds. Previous studies have estimated that between 8 and 10 million birds die from lead poisoning each year including Bald Eagles, Golden Eagles, hawks, ravens, vultures and Mourning Doves.

"Here we have another peer-reviewed study with independent scientists confirming that lead is needlessly and tragically killing protected wildlife. While the nation has removed the lead from paint, gasoline, children's toys, water pipes, and even car wheel weights, we are still using toxic ammunition," Schroeder said. "Acceptable lead-free alternatives exist, and we need every hunter in America to make the switch to save the lives of countless non-game birds."

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