This surprised me. By now, I am used to the usual suspects of species degradation: urban sprawl, loss of habitat, pollution, shrinking resources. Those are almost always given as the explanation for why a particular species is threatened or endangered.

Not so with the California condor. Those factors certainly put pressure on the condor to survive in California, but surprisingly, there is one factor that trumps all of those, according to wildlife biologists.

Lead bullets.

Not because condors are shot by guns with lead bullets – no, lead bullets are dangerous to condors because they eat them.

Condors are like vultures; they feed on carrion. Dead animals. And many animals in the wild die when they're shot by hunters. So when an animal is shot, and then gets away from the hunter before it dies, or when a hunter guts an animal in the field and leaves the remains behind, that meat has lead fragments in it. So it's easy for California condors to ingest lead, and that can be fatal.

Lead has been shown to be hazardous to humans in even small amounts. Condors weigh about 20 pounds, so it doesn't take much lead to harm them.

The state legislature passed a law in July that bans lead bullets from areas with condors, from the San Francisco Bay Area south to San Diego.

Hunters are reluctant to simply throw away all of their lead ammunition, though, to purchase copper bullets at a higher price. And many of them are unaware of the law – or unaware that the ammo they're using is lead. Many lead bullets are topped with copper, so they look like copper bullets. This not only makes it hard for hunters to identify which of their bullets are lead-based, but it makes it difficult for state parks rangers to identify them, as well.

Listen to the Condor Return radio report online.

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There we were, 12 Oakland Zoo staff, winding our way down the Big Sur coast. We were spending a clear, bright Sunday morning with Sari, a biologist from the Ventana Wildlife Society, in hopes of learning about condors and perhaps catching a glimpse of this highly endangered bird. On route from the Ventana Wildlife Society's rustic outpost office in Andrew Molera Park, Sari told us a bit about condor history, her work and the nature of condor breeding.

The California Condor was at the brink of extinction due to habitat loss, poaching and lead and DDT poisoning. In 1987, the US government approved a captive breeding program and the 22 remaining condors were captured and bred at various California zoos with the help of the Ventana Wildlife Society. Now 147 California Condors live freely and are beginning to reproduce in the wild: a true conservation success story!

Though lead poisoning is still a threat (see Quest Piece), conservationists hope that recent lead bullet legislation will bring that threat to an end. The Ventana Wildlife Society also trains their charges to avoid electrical wires, another challenge to their survival.

Sari's job is to monitor all of the 42 condors that call Big Sur home. She tracks them with antennae that pick up their radio tags every day, and if 5 days go by without seeing one of them, she goes on a mission to find them. Not surprisingly, Sari loves her job.

Us zoo folk were most impressed by their unique breeding story. Condors do not successfully reproduce until age nine and then lay only one egg every two winters. Once hatched, the chick stays in the nest for six months, completely dependent on parental feeding and care. Even after fledging, the young condor sticks with the parent for another year or so. This is a lot for a bird and it is no wonder that bringing the population back from the brink requires some help.

Finally, we stopped just a bit north of Julia Pfieffer Park and piled out:

Big Sur, big cliffs, big sky, big expectations…and then there they were…really BIG BIRDS! Three condors sat on pines not too far from us, bending the tips of the tree with their weight. Through Sari's scope or binoculars, we could see their radio tag numbers, their bald pink heads, their feathery, boa-like neck feathers and their giant bodies.

As we observed their behaviors of submissive biting and displacing each other on their chosen perches, random people stopped their cars to see what we were up to and Sari took time to talk to each newly inspired condor enthusiast.

Then, against all seeming odds, they lifted their bodies, displayed their nine and half feet wingspan, and soared right by us…once, twice, three times. They seemed to be riding the wind, representing everything good that we humans can do for nature, once we try.

You, too, can take a tour with Ventana, every second Sunday of the month.

Visit "Bringing the Condors Home," a fantastic condor exhibit that will be at The Oakland Zoo this September.

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