Despite years of costly conservation efforts, extremely rare California condors are still dying from lead poisoning as a result of scavenging on carcasses contaminated by lead bullets.
Conservation and contamination
The California condor, the largest and most threatened wild bird species in the United States, has been teetering on the brink of extinction for more than three decades, with just 22 individuals remaining in 1982. Thanks to intensive conservation efforts, this iconic species has made a modest recovery in recent years, with the total population increasing to about 400 individuals, half of which are in captivity.
Yet recent research indicates that it is still too soon to celebrate; without the continuation of the extensive support given to the California condor, including the millions of US dollars which are put into its conservation each year, it will not be able to persist in the wild.
Lead poisoning, as a result of scavenging from carcasses contaminated by lead bullets, remains a lethal threat to this Critically Endangered bird, and recent research has revealed that unless hunters change their practices, this iconic species faces an uncertain future.
The troubling data, released in a report this week, suggests that the California condor is currently facing an ‘epidemic’ of lead poisoning, despite a state-wide ban on the use of lead shot in key regions back in 2008. The research indicates that the number of chronic poisoning cases has not decreased in spite of the attempts to limit the use of lead bullets.
“We will never have a self-sustaining wild condor population if we don’t solve this problem,” said Myra Finkelstein, a research toxicologist at the University of California Santa Cruz and one of the authors of the study.
The ban on lead shot was met with fierce resistance from gun rights groups, but this new study has provided further evidence that the lead which is poisoning the California condors is the type which hails from lead bullets. “Unfortunately, even if only a few people are still using lead ammunition, there will be enough contaminated carcasses to cause lead poisoning in a significant number of condors,” said Ms Finkelstein.
The inefficiency of the lead bullet ban has been blamed on a lack of resources to enforce it, including a lack of game wardens, which means that the future of the California condor now depends on the goodwill of hunters.
“Kudos to the hunters who are using copper [bullets], but it isn’t going to be effective until you get all the lead out,” said Jeff Miller, conservation advocate for the Center for Biological Diversity (CBD), based in Tucson, Arizona.
As part of conservation efforts, California condors are currently tagged and monitored, and are trapped twice a year for blood tests. The latest study has showed that approximately 20% of condors in the wild have blood lead levels that are high enough to require costly treatment to remove the toxins from their bodies.
Furthermore, since 1997 around half of all free-flying condors in California have required some form of veterinary treatment for lead poisoning. Without this medical intervention, the birds suffer paralysis, stiff joints, and lose their ability to fly. Should blood lead levels become too high, the birds can die.
“Lead exposure and poisoning levels in condors continue to be epidemic,” said co-author Dan Doak, a professor in Colorado University-Boulder’s Environmental Studies Program. “Despite the current efforts to help the species, the wild population will decline again toward extinction in a few decades unless these unsustainable and very expensive efforts continue in perpetuity.”
Read more on this story at Scientific American – California condors face menace of carcasses laden with bullet lead.
Find out more about the California condor on ARKive.
Kathryn Pintus, ARKive Species Text Author