Chris Parish, who has worked with California condors since their reintroduction near the Grand Canyon since 1997, says that lead is the bird's worst enemy.
"If you look online, it lists habitat loss, shooting and egg collecting as their reason for near-extinctions," said Parish, with the Peregrine Fund, an organization that tracks and researches the California condors.
"But we are learning what the true threats are from the reintroduction programs, and that is lead," Parish said. "Fifty-three percent of our diagnosed deaths are lead poisonings."
In 1991, lead shot ammunition was banned, Parish said, but that didn't solve the problem.
Bullets still have lead in them, he said.
Those bullets fragment upon impact and if a condor consumes the fragments, they get lead poisoning.
Parish said condor advocates worked together with hunters in the Kaibab Plateau to eliminate bullets containing lead.
"If someone shoots a rabbit, for example, and leaves it in the field, birds are going to be potentially poisoned," Parish said.
Although lead-free bullets can be more expensive, Parish said if you compare them with other "high quality" ammunition, the cost is comparable.
"The most important thing is the process of education," Parish said.
In 2008, The Peregrine Fund organized a conference titled "Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans" in Boise, Idaho. It drew 150 professionals from the fields of human health, wildlife health, management and conservation, outdoor sports and hunting and public policy to hear research, discuss solutions and share expertise.
Each year since 2000, The Peregrine Fund has trapped almost every condor in the Arizona flock and tested each for lead exposure. If they've ingested fragments of lead in carcasses or gut piles from game animals shot with lead ammunition, the condors become sick or die unless they are treated to remove the lead from their system.
The Peregrine Fund has partnered with the Arizona Game and Fish Department on an awareness program that has resulted in hunters voluntarily switching to non-lead ammunition in condor country.
A similar effort is under way in Utah after condors expanded their range there during the hunting season.
"It's something to think about in southwest Colorado too, since they have been spotted there," Parish said.