Rats decimating seabird colonies on Kiska Island

Posted: Sunday, July 13, 2003

ANCHORAGE (AP) Norway rats are decimating one of the Northern Hemisphere's most spectacular seabird colonies.

The rats are eating auklets nesting at the base of a volcano on Kiska Island, near the tip of the Aleutian Chain.

Scientists visiting the site during the past three summers say the devastation is extreme, leading to many empty bird-nesting crannies in the jumbled lava overlooking the Bering Sea.

''The rats will just go from one nest to the next thousands and thousands and thousands of adults and chicks getting their brains and eyeballs eaten from their heads,'' seabird ecologist Ian Jones said. ''It's a really horrible show. There's no other way to describe it.''

Federal scientists are now trying to figure out whether the rats can be eliminated with poison, though Kiska would be the largest island where that has been tried. It may be the only way to save one of the Pacific's natural wonders.

Each summer, 3 million to 6 million least and crested auklets and other birds return to Sirius Point in flocks. But a study in its third year has found adults dying or abandoning nests, leaving chicks to starve or get mangled.

Last year, surveys found that only one-tenth of least auklet eggs hatched chicks that flew away the lowest reproductive success ever observed for the species, which forms 80 percent of the colony.

''What we suspect at this point is this colony could well be gone in 20 years or so,'' said federal biologist Art Sowls, with the Alaska Maritime National Wildlife Refuge.

The dramatic spread of rats on Kiska is one more crisis in a worldwide rat plague that threatens other important nesting sites in Alaska.

Rats have made it to at least 21 large Alaska islands, not counting islets. They got to Kiska, part of the Rat Islands group, during World War II and gradually overran much of its rugged 70,000 acres.

But it was only during the past decade that scientists realized the full extent of the danger to the auklets, which live in the crumbling lava only a few months a year.

''It is an enormous disaster,'' said Jones, an Iowa-born associate professor of biology at the Memorial University of Newfoundland, who has done field work in Alaska for the past 18 summers. ''The number of seabirds that are being killed by rats each year (on Kiska) are more than what were killed by the Exxon Valdez oil spill.''

An ambitious experiment to poison rats at Sirius Point late this winter or next is now under development, said Peter Dunlevy, a refuge biologist.

Biologists may put out a government-approved bait called Ramik Green, which contains an anti-coagulant that causes the rats to die of internal bleeding.

If the rats get knocked back at Sirius Point in 2004 or 2005, the refuge would then try to get permission to broadcast the bait from aircraft to eradicate rats from the whole island, said Vernon Byrd, the refuge's supervising biologist.

This work on Kiska is part of a broader campaign to drive rats from other refuge holdings, like Rat Island, and keep them from invading bird colonies on St. Paul, Buldir and other islands.

Scientists have used poison to remove rats from islands off New Zealand and British Columbia. The biggest island where it has worked is 27,900-acre Campbell Island, about 440 miles south of New Zealand. Kiska is more than twice as large.

''You have to kill every single rat,'' Dunlevy said.

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