The last six California condors living in the wild will be captured early next month in an effort to save North America's largest bird from extinction, even though a prominent wildlife group opposes the plan.

After six condors died last winter in the wild, federal wildlife officials decided to snare three of the surviving birds, said Meg Durham of the U.S. Fish and Wildlife Service in Washington.

Last week, acting U.S. Fish and Wildlife Director Ron Lambertson authorized capturing all six birds, two of them females -- a move opposed by the National Audubon Society, because the only female condor that bred successfully in the wild last year has a high level of lead in her blood, Durham said. Biologists say high levels of lead found in several other condors indicate that the scavenger birds may have eaten bullet-poisoned animal meat.

Twenty-one of the birds, vultures with wingspans reaching nearly 10 feet, live in captivity, but most are too young to breed, Durham said.

"We've come to the decision to take all six very reluctantly," she said. "We want to make sure they stay safe until we're sure we've got a good breeding program. We don't want to lose any more -- there are too few of them already."

Linda Blum, an Audubon Society habitat specialist, said the birds' rugged homeland, mountains 60 miles northwest of Los Angeles, might be targeted for development once the condors are removed.

"All the things that need to be done as far as protecting and preserving habitats and eliminating mortality factors -- all those things are not going to get done if there no birds in the wild," she said.

Eleven of the birds now live at the Los Angeles Zoo and 10 at the San Diego Wild Animal Park.