The number one killer of wild California condors is lead poisoning. Hunters shoot game animals with lead ammunition, and leave the bullet/cartridge fragments in the carcass. Condors have exceptionally strong digestive acids, which means that they actually digest the ammo and the lead enters their system, eventually killing them. Despite outreach programs and publicity campaigns pleading with hunters to stop using lead shot, the deaths continue. Some ecologists believe that the population of wild condors will only become sustainable if the use of lead shot is outright banned, which will not occur until at least 2019.
The coastal populations of condor are less vulnerable to lead poisoning, but another threat has raised its ugly head; mercury and DDT. DDT dumped into the ocean from the 1940s to the 1970s is still making its way through the food chain, and is now being found in high concentrations in the fat of marine mammals such as whales and sea lions. When the carcasses of these animals wash up on the shore, condors devour the tainted fat, which then causes females to lay thin-shelled eggs that are often crushed by the weight of the parents. It’s estimated that the chance of a condor in this area successfully hatching an egg is only 20 to 40 percent.