The California condor is big. In fact, it's the largest flying bird in North America with a wingspan of 9 1/2 feet.
Michael Mace, curator of birds for the San Diego Zoo Safari Park, tells NPR's Arun Rath that the condor "is like the 747 compared to a Cessna if you look at it proportionally with other species like eagles and turkey vultures."
Mace works in a condor power line aversion training program at the zoo. It was developed to address the condors' unfortunate run-ins with power lines.
"When they're flying, there's no reason to look forward because they're scanning the earth looking for carrion," Mace explains.
Because the birds have no reason to look forward, they fly into power lines and risk electrocution. On top of that, when the condors are looking for a place to sleep, they land on power poles and structures, and get electrocuted there too.
Their large size makes them more vulnerable to electrocution than smaller birds, because they're more likely to touch two lines at once. (Touching just one wire is safe, which is why many birds land on power lines without consequence).
And each death is worrying. The California condor was on the brink of extinction just a few decades ago, and today there are still fewer than 500 in the world, Mace say.
He and his colleagues at the zoo are trying to use aversion training to undo years of evolution that told the birds not to be worried about things like power lines.
"When we started to realize what was occurring, we wanted to look at a way that we could modify their behavior," Mace explains.
Working with local utility companies, they installed power poles inside the condors' enclosures.
"We wired those poles to deliver a very mild electric charge — nothing harmful — but something that a bird would realize that it was not a comfortable place to be," Mace says.
This aversion training isn't meant to go on indefinitely, though. Eventually, the condors in the program will start to produce their own offspring. As parents, these condors will teach their chicks how to survive in the wild — including avoiding the power structures.
"What we're seeing is the chicks follow the parents' lead and don't do it either," Mace says.
The next generation of power line-averse birds is almost ready to graduate into the real world: Mace says the San Diego Zoo Safari Park will send three birds who have undergone the aversion program to field sites in California and Arizona for release in September.
ARUN RATH, HOST:
A fight for survival - on one side, a huge bird. You might even call it a modern-day dinosaur.
MICHAEL MACE: So the California condor's the largest flying bird in North America, and it has a wingspan of nine and a half feet.
RATH: Michael Mace is the curator of birds at the San Diego Zoo Safari Park.
MACE: So in the bird world, it is like the 747 compared to a Cessna if you look at it proportionally with other species like eagles and turkey vultures.
RATH: But the king of the birds is in a knockdown, drag-out fight with a formidable adversary, a foe it never saw coming - power lines.
MACE: When they're flying, there is no reason for them to look forward because they're scanning the earth, looking for carrion that they feed on or other items on the - on the surface. And so when they develop, they had a reason to look forward, and so they would fly into power lines, for example, on ridgelines of mountains. Or - condors like to roost, and when they would go to roost, they would land on these power poles and power structures and would become electrocuted because they're such a big bird. It's very easy for them to touch wires.
RATH: So how to do you go against 10,000 years of evolution that told the birds not to be worried about this kind of thing?
MACE: So when we started to realize what was occurring, we wanted to look at a way that we could modify their behavior - change their behavior so that we could keep them out of harm's way. So we developed a technique working with our local utility companies to use their power poles that they have and install those within the enclosures here at the Safari Park. And then we wired those poles to deliver a very mild electric charge - nothing harmful, but something that a bird would realize that it was not comfortable place to be.
RATH: Now, will you have to be doing this aversion training with the birds indefinitely, or will there be a point at which they figure it out?
MACE: That's a really good question. So one of the goals of the condor program is to have a sustainable population in the wild. And so as those birds that we're releasing then are of age to where they're sexually mature and starting to produce their own offspring, the fact that those parents are teaching their chicks for a couple years how to survive in the wild - if the parents are no longer visiting the power structures to roost on, what we're seeing is the chicks follow the parents' lead and don't do it, either.
RATH: So when is the group of condors going to be released? When is your next graduating class?
MACE: Well, we're actually getting ready this next month in September here at the San Diego Zoo Safari Park to send three birds that were raised here to the field site in California and the field site in Arizona to be prepared for release months from now. So the next generation is ready to go out. So when we started this program, you know, we were challenged with a species that's almost went extinct. The condor, in 1982, only had 22 birds left in the world. There are now more than 420 condors in the world, of which more than 230 of those are now flying free in California, Arizona and Baja, Mexico.
RATH: Michael Mace is the curator of birds for the San Diego Zoo Safari Park. He works in the condor power line aversion training program at the zoo. Michael, it's been great speaking with you. Thank you.
MACE: Thank you for the opportunity to talk about the California condor.
(SOUNDBITE OF SONG, "BIG BIRD")
THE B-52S: (Singing) There's a big bird flying over my house. Go away. Go away. There's a big bird flying over my house, and it looks like it's decided... Transcript provided by NPR, Copyright NPR.