Rat Island, no more

VICTORIA BARBER

May 02, 2008 at 10:13AM AKST

By next winter, Rat Island will be in need of a new name. The Alaska Maritime National Refuge, in partnership with Island Conservation and the Nature Conservancy, has announced that it will move forward with an effort to exterminate the entire rat population of the uninhabited island this fall.

The rats will meet their fate via a helicopter airdrop of rodenticide. It’s the first time a whole-island rodent extermination has been attempted in Alaska.

The rats infested the island after a shipwreck in the late 1700s. State scientists believe that since then, they have decimated seabirds and other native species. The refuge hopes that once the rats are gone, the native bird populations will flourish on the island once more.

Steve MacLean, Bering Sea program manager with the Nature Conservancy, said that exterminating the rats is expected to cost between $2.8 million and $3.1 million, depending on how smoothly the operation goes. He said that the majority of the funding has been drawn from private donors and settlement funds from oil spills.

When it came time to pick the poison, the refuge chose a highly lethal anticoagulant called brodifacoum, the same chemical you’d find under a variety of trade names in a hardware store for the pests in your backyard.

The poison will be dropped in the form of bait and, if all goes according to plan, every square foot of rat territory on the island will be coated with the stuff.

"We have to get into every rat burrow," said Poppy Benson, public programs supervisor for the refuge. "We have to succeed the first time because rats breed so fast – if there are any rats left it will all have been for naught."

Benson said that wide-scale poisoning is the only chance the refuge has of getting all the rats in one outing and restoring birds to the island.

Two helicopters will take two months to make the killing. Guided by GPS, the helicopters will systematically drop the bait over one swath of land at a time.

It’s not an easy job – the pilots will have to make sure the poison is distributed evenly while contending with stormy weather conditions.

That’s why the refuge looked outside Alaska for expertise, hiring two New Zealand pilots who have handled island-wide eradications in the past. Benson said that some local pilots will train with the experts so that they can perform similar operations in the future.

Gregg Howald is a biologist and program manager for Island Conservation. He said that of the 300 whole-island eradications that had taken place around the world, the majority had used the brodifacoum rodenticide.

He said that studies of California water systems and sea life after an extermination on Anacapa Island, where brodifacoum had been administered to black rats, showed no ecosystem effect from the chemical.

However, that does not mean that other animals aren’t endangered by the poison. While studies of rat behavior showed that about 80 percent will go underground to die, there is a chance that some birds could peck at the dead rats and die from poisoning.

Howald said that the refuge is planning to monitor island for bird deaths after the rodenticide has been dropped.

"Strictly from a toxicology standpoint, yes, birds could be affected," Howald said. "We could lose a few birds, but the point is that once this project is completed we won’t have to go to the island in the future, and those birds would have been prey to rats anyways."

"In short order, once the rats are gone, the ecosystem of the island will restructure," Howald said.

The refuge is hoping to mitigate potential bird fatalities by scheduling the eradication for fall, after most of the bird population has migrated. By the time the birds migrate back to the island, the rat carcasses will have long since decomposed, and the poison will have broken down into carbon dioxide and water.

Benson said that if the Rat Island eradication is successful, the refuge might move forward to get more of the Aleutian Islands rat free.

"Kiska is a real concern," Benson said. "Most bird experts say that the Kiska auklets are doomed if something doesn’t happen."

Benson said that the public response to the initiative has been overwhelmingly positive. However, she has had comments from people who don’t believe the refuge should kill rats.

"People focus so much on the rats, but the story not just that we’re killing rats, but we’re making birds," Benson said. "With so many bird species declining worldwide, how wonderful will it be to create new bird habitat?"

Victoria Barber can be reached at (907) 348-2424 or toll free at (800) 770-9830, ext. 424.