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Rat Island's reviled namesake is targeted

The invasive rodents landed on the Aleutian isle in 1780, wiping out local birds. Now a plan aims to eradicate the unwelcome inhabitants.

December 09, 2007|Mary Pemberton | Associated Press

ANCHORAGE, ALASKA — More than 200 years ago, rats were shipwrecked on an Aleutian island.

The stocky, muscular Norway rat jumped the Japanese sailing ship and soon had full run of the rugged, uninhabited island in far southwest Alaska. It was 1780, the first time the invasive rodents made it to Alaska. A subsequent visitor dubbed it Rat Island.

Since then, Rat Island has gone silent. Not even the chirping of birds is heard there.

"There is a silence to an island with rats," said Steve Ebbert, a wildlife biologist at the Alaska Maritime National Wildlife Refuge, where the aptly-named island is one of 2,500 islands stretching along Alaska's long southern edge. "As far as bird life, it is a dead zone."

Seabirds and ground-nesting birds have no natural defense against the rodents.

State and federal wildlife biologists are gearing up for an assault on the rats of Rat Island, 1,700 miles from Anchorage. The goal is to wipe out the rodents. If successful, Rat Island would be the third-largest island in the world to go rat-free.

A visitor stepping onto the island in the Aleutians won't have to look far to find evidence of rats, said Jeff Williams, another refuge biologist. Among the first signs are the rat burrows and rat trails through the vegetation. Then there are the rat droppings, the chewed vegetation, the lack of certain plants.

"You go to Rat Island and there are hardly any chocolate lilies," Williams said.

Ditto for birds.

Rats now inhabit about a dozen large islands in the refuge -- which is home to an estimated 40 million nesting seabirds -- and many smaller islands where they prey on eggs, chicks and adult seabirds, which come to the mostly treeless islands to nest on the ground or in cracks and crevices in the volcanic rock. Puffins, auklets and storm-petrels are most at risk because they are absent from their eggs and young for extended periods while foraging away from the coast.

Norway rats typically have between four and six litters a year, with six to 12 babies each. One mating pair can produce a population of more than 5,000 rats in one year.

"Rats are highly prolific," Ebbert said.

Like a sequel to a horror film, biologists watched three years ago as a 738-foot freighter from Singapore lost power in the Aleutians and began floating toward Bogoslof Island. Bogoslof is rat-free. The soybean freighter most surely had rats.

The freighter ended up breaking in two off Unalaska Island -- no big deal because Unalaska already is infested.

Rats have been the scourge of islands worldwide. According to the California-based group Island Conservation, rats are to blame for 40% to 60% of all seabirds and reptile extinctions, with 90% of those occurring on islands.

"Rats are one of the worst invasive species around," said Gregg Howald, program manager for Island Conservation, which is working with the U.S. Fish and Wildlife Service and the Nature Conservancy on a plan for Rat Island. "If you go to Rat Island, one thing you will notice is that it is eerily quiet compared to the other Aleutian Islands that are literally brimming with life."

The state is joining forces with federal wildlife biologists in a multi-pronged attack on the rats. The effort will be launched on several fronts: shore-based prevention, ship-based prevention, shipwreck response and island eradication.

Biologists can only guess what Rat Island was like without rats. It was dubbed Rat Island by a sea captain 50 years after the first rats arrived.

"The seabirds are so obvious when you're on a rat-free island, and they are so noticeably missing on an island that has rats," Ebbert said.

The rats, just as they do now, jumped ship beginning in the late 1700s. The problem worsened in the 1820s, when rats aboard Russian merchant ships began to infest the islands. The problem got worse still during World War II when hundreds of military ships visited the Aleutian Islands.

Now, the islands are vulnerable to "rat spills" from tankers taking the quickest route from the West Coast to Asia. Ships make an estimated 3,000 passages a year through Unimak Pass in the Aleutians. The Aleutians receive about 400 port calls from vessels each year.

Kiska Island is the only Aleutian island with rats that still supports a large seabird colony. But warning flags have been raised. Rat caches containing more than a hundred auklets have been found in rat dens. The rats open up the back of the skull and usually eat the eyes and brains.

Alaska recently issued a 172-page plan to limit rats by bringing together federal, state and local governments, as well as nonprofit organizations, to rid Alaska of rats and prevent more from arriving. An interagency group, the Alaska Rodent Action Team, is being formed.

Coastal communities, where rats spread easily via vessels and shipping, are on the front lines of the battle. About a dozen coastal communities in Alaska harbor breeding populations of rats. Rats make it inland aboard aircraft and barges.

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