New study: Lead poisoning of condors at 'epidemic proportions'
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By Paul Rogers
Posted: 06/25/2012 12:21:53 PM PDT
California condors, one of the world's most endangered species, are facing lead poisoning from hunters' bullets "at epidemic levels," and will not recover unless further steps are taken to control it, a new study Monday found.
A review of more than 1,154 blood samples taken from wild California condors and tested between 1997 and 2010 found that 48 percent of the birds had lead levels so high that they could have died without treatment in animal hospitals.
So far, even a ban on lead bullets in the birds' habitat appears to have had little effect, the study found.
The reason, said Finkelstein, is because a condor
can dine on between 75 and 150 dead animals a year.
"If just one has a lead bullet fragment, that can be enough to kill the bird," she said.
Today the California condor population has grown to 386. Of those, 213 live in the wild at Big Sur, Pinnacles National Monument in San Benito County, Southern California, Arizona, Utah and Mexico. The other 173 condors live in captivity, at places such as the Los Angeles Zoo.
Although the population growth has been impressive, it is deceptive because it is highly dependent upon human intervention, the researchers said in Monday's study, which was published in the Proceedings of the National Academy of Sciences.
Every free-flying condor has a radio or GPS collar to track it. Nearly all of them are captured twice a year and tested for lead. A few chicks have been born in the wild, but biologists still leave out food, such as stillborn calves, for the birds to eat so their population can have a chance to grow.
Researchers were surprised, Finkelstein said, by the extensive poisoning.
For example, 30 percent of all condors captured every year have lead levels that, while not potentially fatal, can block reproduction and cause immune system problems.