X-rays taken at the zoo turned up shotgun pellets embedded in its flesh, she said. Those wounds had healed.
It could not be determined if the pellets were lead or steel, but the poisoning was most likely caused by the bird ingesting spent lead ammunition in carcasses of animals that had been shot by hunters, Kasielke said.
Condors are carrion-eaters and such poisoning by lead ammunition has long been recognized as a problem. California requires hunters to use only non-lead ammunition in the condors' range. It is also illegal to shoot a condor.
Giant California condors are an endangered species, and the federal government has been working for years to establish breeding populations in the wild.
The ailing condor, a nearly 7-year-old dubbed No. 286, was a dominant member of a flock on the central California coast until late January, when biologists from Pinnacles National Monument and the Ventana Wildlife Society noticed it was suddenly being pushed around by younger birds, the conservation society said.
Biologists tried to capture it because the behavior indicated health problems. They were unsuccessful until March 4, when it appeared wobbly on its feet. Tests showed a potentially fatal lead exposure and the condor was sent to the zoo.
Kasielke said that if the condor survives it would stay at the zoo for several weeks, but could be returned to the wild.