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When the Killing’s Done, Island Wildlife Roars Back

Posted by Richard Conniff on March 21, 2016

The world's only oceanic hummingbird, the Juan Fernandez Firecrown. (Photo: Island Conservation)

The world’s only oceanic hummingbird, the Juan Fernandez Firecrown. (Photo: Island Conservation)

My latest for Takepart.com:

For conservation biologist Holly Jones, one of the best experiences of her work on island wildlife was the night she went out hunting for a rare lizard-like creature called the tuatara on Stephens Island in New Zealand. The place was cacophonous with seabirds, which also happened to be attracted to her headlamp. At one point, she found herself sitting in the dark with birds in her lap, at her shoulders, and flapping endlessly around her head. It was like Hitchcock’s The Birds, she said, except that she was ecstatic to be part of this island explosion of life.

Stephens Island happens to be the site one of the most notorious episodes in the history of humanity’s enraptured—but rocky—affair with islands. In 1894, a crew of lighthouse keepers arrived there, bringing a cat named Tibbles with them. The cat was soon coming back to the lighthouse with small, flightless birds in its teeth. One of them turned out to be a new species, the Stephens Island Wren. Within a year or two, a rapidly expanding community of cats had driven it to extinction. By 1897, there were so many cats killing so many birds that a lighthouse keeper urged the authorities “to employ some means to destroy them.” It took another 27 years, but the successful effort to eradicate the cats was the chief reason such an abundance of seabirds survived to greet Holly Jones that night on Stephens Island.

What happened there is now standard conservation practice around the world to protect the incredible diversity of species on islands. Jones, an assistant professor at Northern Illinois University, is the lead author on a study published Monday in the Proceedings of the National Academy of Sciences that looks at the long-term effects of eradicating cats, rats, goats, pigs, and other invasive mammals from islands. On the 181 islands where biologists have conducted follow-up studies, Jones and her coauthors found that eradication turns out to be

one of the most effective strategies “for protecting the world’s most threatened species.”

That may seem improbable. Worldwide, we now spend about $22 billion a year on biological conservation. In that context, the tens of millions spent annually on island conservation is a pittance. (And both amounts are trivial in the context of, say, the $600 billion the United States alone spends every year on the military.) Islands are also comparatively small: They occupy just 5.5 percent of the planet’s land surface area. But isolation has made them a natural experiment station for biological variation and evolution. So they are home to 15 percent of all terrestrial species—and 37 percent of all critically endangered species on the authoritative Red List maintained by the International Union for Conservation of Nature.

Anacapa, in the Channel Islands off southern California, is a typical success story. The buildup to the eradication of invasive black rats was long and controversial. Outraged animal rights groups filed a lawsuit to stop the killing, and Jones once fielded a call from a protester urging that the rats be relocated instead. (“I was like, ‘OK, what’s your address?’ ”) The protesters were perhaps understandably concerned that no harm should come to any sentient being. They just didn’t understand that this was, in effect, a decision to consign entire species to extinction.

The project was also complicated and expensive, at a total cost of $1.8 million, because Anacapa is home to a deer mouse subspecies found nowhere else in the world and vulnerable to the same poison being used against the rats. So the killing, in 2001–02, had to take place in stages, with the deer mice protected on a separate islet and in captivity, until they could be reintroduced after the rats and the poison were gone.

The main goal was to protect the Scripps’s murrelet, said Nick D. Holmes, a coauthor of the new study and director of science at Island Conservation, a nonprofit working on such projects worldwide. These birds breed in caves around the perimeter of the island, and they were being hit hard by the rats. “But almost immediately after extermination, researchers began to see eggs hatching,” Holmes said, and the young birds were no longer being eaten alive in their nests. The population has tripled since then, and 10 years later the ashy storm petrel, a bird not previously known to have occurred on the island, also began breeding there.

Overall, the new study reports, island restorations are now known to have benefited 236 species, a quarter of them threatened with extinction. Removal of invasive animals has so far enabled four species—the island fox, Seychelles magpie, Cook’s petrel, and black-vented shearwater—to be downgraded to a less risky category on the Red List. After a project on Hauturu Island in New Zealand, a type of petrel that had been thought for 150 years to be extinct reappeared and began breeding again.

The study also notes a few negative effects of eradications, including temporary population declines, because some raptors and gulls accidentally died after consuming poisoned carcasses. In four species, the reduction in population is likely to be permanent. On Australia’s Macquarie Island, for instance, removal of invasive rabbits has forced the brown skua, a seabird, to switch back to natural, but less abundant, food sources.

The results, said Holmes, are “reason to celebrate and to be optimistic. It shows that this type of conservation intervention makes a difference, and it illuminates that there is more work to do.” The study counts 804 islands still eligible for eradication of invasive species. Among them are the Juan Fernandez Islands, off the coast of Chile, best known as the setting for Daniel Defoe’s novel Robinson Crusoe. “This is an incredible place,” said Holmes, but it’s also a complicated project because of the varied topography and the social issues involved in working with the human inhabitants.

The islands are home to the world’s only oceanic hummingbird—and to a menagerie of goats, cats, rats, and rabbits. The invaders will have to go, of course. But the new study demonstrates that the islands’ rich native diversity will then have an excellent chance to flourish again in its once-and-future isolation.

 

3 Responses to “When the Killing’s Done, Island Wildlife Roars Back”

  1. john kennedy said

    Tough decisions for most people who consider themselves “nature lovers, like myself.” I hate to step on an ant or swat a mosquito. I still do those things for practicality. But a clear intentional act such as exterminating cats isn’t small or subtle enough to simply slide by…perhaps rats would be less objectionable. This forces all who take that love of nature more seriously than a cute slogan…or, lets say, see it not unlike one of those paintings of puppies and kitties with big cute eyes, its time to be tough with our emotions. This is obvious if one sees nature in its stark reality…not a world of cute furry things… but an essential but complex..and highly interconnected…system of life. That system includes us. Unfortunately, we often don’t see ourselves as just another life element like every other living thing. We don’t view…and most importantly often don’t act…like our world around us is simply a required balanced biodiverse system, even if we know that is true. We also fail to accept that the way to achieve that critically needed biodiversity is to see to it that we don’t intentionally or carelessly upset its apple cart…which is done in the worst way by destroying the natural flora and fauna systems. Unfortunately, we have done that and continue to do so, from our own backyards to the Brazilian jungles, and islands throughout the world. It is simply time to get smart and get really serious about protecting…and now rebuilding where possible…that biodiverse world which is so needed for our own vibrant survival. Our cute kitties that have been carelessly let loose upon the natural world,as well as all the beautiful plants we have imported from far away and replanted in our yards, must be eradicate. While we are at it, why don’t we all get responsible with our cuddly introduced species pets, and keep them indoors or on a leash?

  2. Dick, Very informative article. I particularly like the idea of sending the rats to the fellow with intense feelings for all sentient beings. As know I’m very skeptical about the use of chemicals in the attempts to control or eradicate an undesired pest. The die off of lobsters in the LIS in 1999 likely due to the irresponsible use of chemicals. So before we go off on an eradication program, the precautionary rule should be observed. Let’s be certain no other unintended consequences result from the application of the measures to eliminate the problem. I would recommend that independent studies be done rather than relying on the EPA for guidance. The EPA process for evaluating the safety of chemicals, in my opinion, is seriously flawed.

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