ARI SHAPIRO, HOST:
It's really hard to reintroduce a species to a place where it's died out. Scientists are trying on Socorro Island off the west coast of Mexico. They're returning a cinnamon-colored bird called the Socorro dove back to its ancestral home. Reporter Loretta Williams traveled to the island with one of the scientists leading the effort.
LORETTA WILLIAMS, BYLINE: Socorro is part of an island group nicknamed the Mexican Galapagos. This is not a resort with beach-side cabanas. The only residents are part of the Mexican navy, who today help us navigate through an unforgiving thicket.
All I can say is ouch. Ouch, ouch, ouch.
In the 1920s, the California Academy of Sciences noticed island birds and animals were disappearing fast. So the academy sent an expedition to Socorro with instructions to bring back live doves. The terrain those researchers hiked a century ago is the same ground I and Juan Martinez, a scientist with Mexico's Institute of Ecology, hiked today.
JUAN MARTINEZ: We're going to camp in that area there, where you see the green...
WILLIAMS: Yep.
MARTINEZ: ...And the red.
WILLIAMS: OK.
MARTINEZ: In that area is a heavier forest. That is where they found the Socorro doves.
WILLIAMS: And those are the ones that they brought back, right?
MARTINEZ: Yes.
WILLIAMS: The live ones.
MARTINEZ: That's why all this exercise is helping us to find the locations. The best place to bring them back is a similar place, where they found them.
WILLIAMS: That original expedition brought back 17 doves and sent them to zoos in aviaries in the U.S. and Europe. The plan was to breed them in captivity. At the zoos, they survived. But on the island, they did die off. The reason for that, says Martinez...
MARTINEZ: Here on Socorro, you have introduced sheep, introduced cats and introduced mice.
WILLIAMS: Cats and mice prey on birds and their eggs. But the biggest problem, says Martinez as he points to the hillside, was the sheep.
MARTINEZ: In that hill, that's probably the highest point where they completely removed the vegetation.
WILLIAMS: The sheep, which were more like burly bighorns than woolly lambs, chewed and trampled their way through the forest, destroying the Socorro doves' home.
MARTINEZ: And at the end, all of that material goes to the sea. And it's tons and tons of soil that were lost by the impact of sheep.
WILLIAMS: Martinez and his colleagues have spent the last several years aggressively removing sheep and replanting native trees. There's also ongoing work to rid the island of cats and mice. Even with all that work, you just can't open a cage door and release some doves.
MICHELLE REYNOLDS: Reintroductions are full of uncertainty in most cases.
WILLIAMS: Michelle Reynolds is a biologist for the U.S. Geological Survey and a reintroduction specialist. She knows of Hawaiian ducks that were once moved from one island to another only to take off over the open ocean, never to be seen again. Expect surprises, she says, even after removing the old threats and returning the doves to Socorro.
REYNOLDS: There could be a new threat, one that didn't exist when the species used to live there.
WILLIAMS: For example, says Reynolds, avian diseases such as West Nile are more prevalent now. Another unknown - how captivity changed the birds. The doves may have lost traits needed in the wild.
REYNOLDS: You might lose some aggression. You might lose vigilance. There's lots of characteristics that can change over many, many generations in captivity.
WILLIAMS: Back on Socorro, Martinez admits this might seem like a lot of work for one small species on one small island. But, he says, other birds here are teetering on extinction. He and other scientists believe the effort to return the dove to Socorro will also help those endangered species.
MARTINEZ: It's not restoration by restoring or reintroducing one species. At the end, what you want is to restore the ecological interactions that interplay on the island. And once you do that, the island will go back to its original course.
WILLIAMS: Martinez and his team hope to bring the birds back to Socorro in the coming year and slowly reintroduce them to the wild. It's a process the scientists a century ago might never have imagined. And it's an undertaking Martinez also might not see the end of. It could be decades before the doves can flourish on their own, living and reproducing with the population continuing to grow. Martinez believes it's a long, difficult and costly effort that's ultimately worth it to give the dove and the island another chance. For NPR News, I'm Loretta Williams on Socorro Island.
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