By Susan Milius
The California condor’s return to flying free in the wild after a close brush with extinction may be an illusory recovery.
The hundred-plus condors soaring over California swallow so much lead shot as they scavenge carcasses that the population can’t sustain itself without steady medical care and continual resupply from captive populations, says toxicologist Myra Finkelstein of the University of California, Santa Cruz. She and colleagues describe analyses of lead in blood and feathers June 25 in Proceedings of the National Academy of Sciences.
About 30 percent of blood samples collected annually from free-flying condors in California show lead concentrations high enough to affect the birds’ physiology, Finkelstein and her colleagues report. Each year about 20 percent of the state’s monitored birds flunk their lead test badly enough to need detox.