Defenders Magazine

On the Ground: Return to Rat Island

by Madeline Bodin

Photo by Mark Rauzon/USFWS

No one knows exactly what Alaska's Rat Island was like 200 years ago, after a Japanese sailing ship crashed there, spilling rats onto a bird-rich landscape. Chances are, though, it was much like what Art Sowls found a few years ago as he zigzagged his way across jumbled blocks of lava on Kiska Island—a neighboring island near the western end of the Aleutian chain, which is strung like a necklace across the Bering Sea.

Sowls, a wildlife biologist with the Alaska Maritime National Wildlife Refuge who recently retired, was mapping the island's auklet colony during breeding season. Some three million birds, mostly least and crested auklets, commonly tuck themselves into cracks in lava that flowed from a nearby volcano a century ago. On that treeless, wind-battered island, the lava offers auklets protection from predatory birds such as peregrine falcons.

As Sowls walked, a clump of black-and-white feathers in the grass caught his eye. Moving aside the vegetation, he found a rat burrow. Digging down, he pulled out the cold, still body of a least auklet. More carcasses followed, until he piled together about a dozen sparrow-sized bodies—all the victims of non-native, invasive Norway rats. Because the birds did not evolve with any land-based predators—no rat is native to the Aleutians or the rest of Alaska—they have no defense against the rats. 

Caches of dead birds like the one Sowls discovered are found throughout the seabird nesting colonies on Kiska. Rats, which are thought to have arrived on Kiska Island during World War II when Allied and Japanese troops alternately occupied a military base here, can stash as many as 140 bird carcasses in one place. Many of the caches contain uneaten eggs, too. Some hope that the sheer numbers of auklets—which darken the sky as they approach the island—will allow them to hold their own against the rats on Kiska. But most scientists believe the auklet colony there will be wiped out by the rats in 20 to 40 years.

If that happens, Kiska may turn into what Rat Island is today—a quiet place. The squawking sea bird colonies of the other Aleutian Islands don't exist there, although the habitat is ideal—except for the rats. There are no song sparrows, which are found on most other Aleutian Islands, and few shore birds.

To prevent rats from gaining new footholds in Alaska, Defenders of Wildlife and about a dozen other organizations began working on the issue in 2006, forming the Stop the Rats campaign. The stakes are high. Some 80 percent of Alaska's seabirds—such as puffins, auklets and storm petrels—nest in the region, says Stacey Buckelew of Island Conservation, a California-based organization with experience restoring island ecosystems. When rats are introduced to an island, they waste no time wiping out the nesting bird colonies.

Typically the rats kill the adult birds sitting on their nests, then eat the egg or chick, but just nibble on the adult. In some years, just 10 percent of the eggs in the colony hatch—a fraction of the normal 60 percent to 70 percent hatching rate. With that kind of mortality, it doesn't take the rats long to wipe out a breeding colony.

"We are lucky here in Alaska because we don't have rats everywhere," says Poppy Benson, public programs supervisor for the Alaska Maritime National Wildlife Refuge. But where they do exist on a dozen major islands out of the hundreds of islands that make up the Aleutian chain, these non-native animals pose a serious risk to native wildlife. That is why two helicopters spread grain spiked with rat poison over Rat Island in October in a program carried out by the U.S. Fish and Wildlife Service, Island Conservation and The Nature Conservancy. Since rats are the only land-based mammals on the island, no other mammals were at risk. "Overwintering birds such as rosy finches and winter wrens were at some risk of accidental poisoning," says Benson. "But the refuge examined this issue at length in an Environmental Assessment released in 2007 and concluded those species would rebound so quickly after the rats were gone that any lost to poisoning would soon be replaced." Precision work, such as spreading the bait far enough from the island's lakes to ensure that it doesn't wash in, was done by hand by team members camping on the remote island.

Meanwhile, Stop the Rats sponsors a "rat spill" team that responds to shipping accidents, offers a Web site that provides important information to boat owners and Alaskan municipalities on preventing the spread of rats, and provides free rat-prevention kits. The kits contain a field guide to rat signs, several types of traps and a video explaining Alaska's rat situation to boat owners. The group has also prepared a rat control and prevention manual for ports, harbors and waterfront facilities that provides strategies for rat control and prevention that can be applied anywhere in the world.

If the rat eradication campaign proves successful, scientists expect song sparrows to return to Rat Island along with tufted puffins ancient murrelets and storm petrels.

But can an island that becomes free of rats still be called Rat Island? The organizations involved in the Rat Island restoration say no, and they are already researching alternative names. At the top of the list is Hawadax, which is believed to be the native Aleut name for the island. Buckelew offers another suggestion: "Rat-free Island."