Ending Extinction or Playing God?

Inside a sometimes-violent mission to save endangered animals. An excerpt from Battle at the End of Eden, The Atlantic's first story to be published exclusively as an ebook.

Midway Between the Baja Peninsula and the Mexican mainland, a hunk of volcanic rock named San Pedro Mártir juts out of the warm, productive waters of the Gulf of California. The island spans an area roughly half the size of Central Park and has a beachless shoreline of near-vertical cliffs, some surging as high as 500 feet. No humans live here. Instead, it is a mecca to tens of thousands of land and seabirds. For centuries, more than 80 species, from brown pelicans and frigate birds to warblers and kingfishers, have vied for purchase on its stony outcroppings. As a result, its lower slopes are slathered with a coating of bird guano so thick that the island, when viewed from a distance, appears bone white.

In 1885, prospectors from the Mexican Phosphate and Sulphur Company glimpsed San Pedro Mártir's gleaming white bulk, and saw gold. Guano is rich in nitrogen and phosphorus, elements in constant demand for use in fertilizer and gunpowder.

The miners' impact on the island was severe. As they trampled thousands of nests, the birds abandoned their colonies, and the ridgelines began to erode under the stress of relentless excavation. By 1888, the island had more or less been picked clean, and the operation shut down.

A century passed, and by all appearances, activity on the island proceeded as it had for hundreds of years. In March 1990, a Ph.D. student named Bernie Tershy set up camp there to study the island's seabirds--he was struck by something surprising. All over the island, black rats menaced the birds; they infiltrated the colonies, pilfered the eggs, and preyed on the young. At some point during the guano excavations--likely as one of the many supply ships hugged the rocky coast--the rats had scampered ashore. Now, all these years later, as Tershy tracked the birds, he watched helplessly as the rats ate his data. "The birds get oil for their feathers from a gland above their tails, and rats like that. It's one of the places they like to start," he explained. They also go for the middle of the back, where "they can run up and chew, chew, chew, and the birds have a hard time shaking them off."

The island was never intended to accommodate rats. With no predators to keep them in check, Tershy knew the rats would just keep killing the defenseless seabirds until the colonies ceased to exist--these birds, that bred only on this rock and a handful of others scattered across the ocean, didn't stand a chance. Perceiving the situation as grossly unfair, Tershy began to think of ways he might relieve the toll the rats were taking.

In the back of his mind was a story he'd heard. In 1958, an ornithologist at the National History Museum of Los Angeles County named Kenneth Stager visited Clipperton Island, a tiny desert atoll in the Pacific Ocean. He'd gone expecting to observe what early explorers had described as massive colonies of tropical seabirds, but what he found shocked him. Feral pigs left by a failed human settlement had decimated the flocks, leaving a mere 650 birds by Stager's count. The survivors had crammed themselves onto an abandoned ship and some rocky ledges offshore, the only surfaces safe from the pigs' reach.

Stager was what Tershy calls an "old-school ornithologist," so naturally he'd brought a shotgun with him. He had planned to use it to collect a few of the birds, but instead, shot every last pig he could find. Thirty years later, when Tershy visited Clipperton, it had transformed. The seabirds were back, nearly 140,000 strong, as were millions of large, orange land crabs that the pigs had also done in. Stager, in his thoroughness, had staged a one-man eradication, allowing Tershy to find an ecosystem with no trace that humans had ever been there. Admiring Stager's brazen willingness to take action, Tershy wondered if he might somehow replicate his success.

He brought his idea to a friend, a biologist named Don Croll, who studied seabirds and whales. The two had met in California in the '80s and had been collaborating on research projects ever since. Croll had had his own encounters with rats ravaging colonies on islands in Antarctica, and was instantly keen to Tershy's idea.

The two decided to adapt Stager's haphazard eradication into a more methodical approach. It was an unusual project for the two young scientists (both were in their early 30s), and it represented something of an affront to scientific culture. To interfere with nature was seen as poor science, if science at all.

Yet, quietly over the next two decades the pair--and a small band of like-minded scientists--would hone eradication techniques that have since saved endangered animals on islands all over the globe. The strategy relies on the choreographed killing of entire caches of animals that don't belong. Like a Delta Force for invasive-species removal, the scientists, operating within an organization called Island Conservation, gather intelligence, craft elaborate plans of attack, and--when conditions are right--strike with traps, hunters, even helicopters that blanket islands with poison pellets. These orchestrated blitzkriegs can last for months or mere hours--and when they're complete, not a single rat, feral cat or goat remains.

They focus exclusively on islands, the places where most of history's extinctions have occurred. Since 1500, of all bird species that have gone extinct, 90 percent lived on islands. Of the reptiles, 86 percent lived on islands, as did 95 percent of the mammals and 63 percent of the extinct plants. Because this remarkable hemorrhage of life has played out on distant shores, it has largely escaped notice. But as experts now warn of a global biodiversity crisis and predict an impending mass-extinction event--the sixth such disaster in earth's history--the fragility of island life has taken on ominous significance. Of the species currently listed as critically endangered by the International Union for Conservation of Nature, almost 40 percent reside on islands.

The outfit that Croll and Tershy started, Island Conservation is now ramping up its ambition, tackling large swaths of islands, and hoping to stave off the global biodiversity crisis with bigger projects than ever. But succeeding will take more than scientific skill. Their methods are highly controversial, requiring guns, poison, and destruction to protect the world's most-fragile species. Hoping to eschew scrutiny, they've mostly avoided public and media attention. But to succeed on the grand scale they now hope to, they will have to face their critics--animal-rights activists who condemn their work as cruel and immoral, fellow scientists who consider their efforts to be hopeless and quixotic, and island residents who aren't in a hurry to make sacrifices in the name of conservation. These scientists will have to make the case that the quest to keep some of the world's most endangered creatures alive is going to involve a measure of death.

This post is excerpted from The Atlantic's new ebook, Battle at the End of Eden. Download the full version here.