After 30 years and millions of dollars spent on California condor recovery, their population has soared from two dozen birds to over 400 today. The largest birds in North America, they have a wing span over nine feet, with a distinctive narrow white triangle on the underside of their black wings. Condors are exclusive scavengers, eating only dead animals.
But condors remain at risk of extinction by lead poisoning. One of their favorite meals, the gut pile that hunters leave behind after killing a deer or wild pig, often contains thousands of tiny fragments from lead ammunition. Until all hunters switch to lead-free bullets, condors will keep dying.
"The lead bullets fragment into hundreds, or if not, thousands of small pieces of lead metal that scatters within the animal that's been shot," says Don Smith, a professor at UC Santa Cruz. He's studied lead poisoning in people, condors and other animals for over 25 years.
Lead Ammunition Bans Expand
We keep half of the condors in zoos for breeding, while the other half suffer from repeated cycles of treatment for lead poisoning. In 2008, California banned hunting with lead ammunition in condor country, but condors continue to be poisoned. Last year the state passed another law prohibiting lead ammunition for hunting statewide, starting in 2019.
Our whole environment is contaminated with lead from many sources, including leaded gasoline and lead paint. Scientists have spent years tracking down the source of lead poisoning in condors.
"By doing a whole bunch of measurements in a whole bunch of condors and lead ammunition from California and other places, we've been able to reach a pretty solid conclusion that the source of lead poisoning for condors is from discarded lead ammunition," Smith says.
Lead Hurt Eagles, Bears, Mountain Lions
It's not just condors that are poisoned by fragments of lead bullets. Lead injures or kills many other wild animals, including golden eagles, bald eagles, turkey vultures, mountain lions, bears and bobcats, according to Smith.
People who eat meat contaminated with lead fragments can be poisoned, too. After California's lead bullet ban, hunters are switching to ammunition made with copper, which is not nearly as toxic as lead. And a copper bullet deforms and stays in once piece when it impacts flesh and bone, instead of fragmenting like lead bullets. But some hunters still use lead bullets despite the ban.
Biologists trap every wild condor a couple of times a year to test for lead poisoning. They draw a sample of blood and put one drop into a portable lead analyzer. If the reading is too high, they treat the bird using chelation, a process that removes heavy metals from the body. Free-flying condors must be kept in captivity for weeks or months during treatment and recovery.
The Next Step in Removing Lead from Environment
After decades of studying the poison, UCSC's Smith can be passionate about removing lead from our environment.
"We've eliminated lead in gas and paints and solder and countless consumer products because of the risk of exposure to people and the environment. There's no reason that we should not be doing this with lead ammunition."
The statewide ban on hunting with lead ammunition starts in 2019. Soon we'll know if that's enough for condors to live free, healthy, and wild without constant treatment.