California condors face risks from lead

A feather as large as a human arm drifts from the azure sky. On Arizona’s Vermilion Cliffs, where the Grand Canyon begins to carve its way into the Colorado plateau, is one of the reintroduction sites for the California condor. And trapping season is underway.

North America’s largest flying land bird, with a wingspan of more than nine feet, is also one of the most endangered species on Earth. The scavengers ingest ammunition fragments when they feed on remains left by hunters, leaving them at risk for lead poisoning. Chris Parish of the Peregrine Fund, a nonprofit based in Boise, Idaho, leads a project here that includes trapping the birds to test lead levels in their blood and detoxifying any with high levels.

Trapping is easy, he says, because the birds can’t resist the stillborn calf carcass lying at the back of a cage.

There are nearly 400 California condors in the world, with more than 200 at reintroduction sites in Arizona, California and Baja California. In 1987, the wild population dropped to just 22. All of the birds were caught for captive breeding, and 16 of them helped to bring the species back from the brink.

The genetic bottleneck has given biologists a first-of-a-kind opportunity to map the genetic diversity of an entire species. Genomes of the 16 birds that gave rise to the recovered population are now being sequenced by Pennsylvania State University and the San Diego Zoo. Once complete, conservationists will know about every gene circulating in the population.

The genomic work will be useless, though, unless the poisonous lead problem is fixed. A recent review concluded that the wild population would disappear without the detox program. Even with it, lead poisoning is a leading cause of death, and action to prevent it is slow to make an impact. California banned lead ammunition inside condor ranges in 2008 but has seen good and bad years for poisoning since. Arizona has taken a voluntary approach to the problem.

Condors enter the cage in midafternoon, and soon they have been corralled into an isolation pen.

Later, the test results arrive: All negative except for one bird. He faces a long, bumpy ride to the treatment facility. But with lead removed via a series of injections, he will soon soar over the Grand Canyon again.

— New Scientist