KTUU.com | Alaska's news and information source | Hundreds of birds die on Rat Island amid rodent eradication effort

Hundreds of birds die on Rat Island amid rodent eradication effort

by Casey Grove
Thursday, June 11, 2009

ANCHORAGE, Alaska -- A "higher-than-expected" number of gull and eagle carcasses turned up recently on Rat Island, a remote 10-square-mile island in the Aleutian Chain that field crews have apparently cleared of invasive rodents, the U.S. Fish and Wildlife Service said Thursday.

Crews dropped poison pellets by helicopter and by hand to kill the rats, which are thought to have been introduced to the island more than 200 years ago by whaling ships, Fish and Wildlife spokesperson Bruce Woods said. The rats have decimated seabird populations, Woods said, because many of the birds nest on the ground and are not used to dealing with predatory rodents.

A survey team this summer saw no sign of rats during a recent two-week-long trip to the island, which is about 1,300 miles west of Anchorage.

But they also collected hundreds of bird carcasses, including 186 gulls and 41 bald eagles, according to a Fish and Wildlife press release.

While biologists always expect to find birds that have either died during the winter on the island or died and washed in from sea, this year's die-off is cause for concern, Woods said.

"Any bird die-off or critter die-off is a concern for us," he said.

It's too early to tell what caused such a large number of birds to die, Woods said.

"It's unlikely to the point of extremely unlikely that the eagles consumed the pellets, but there is the possibility that the eagles ate rats that had consumed the pellets," he said.

Still, Woods said, the project's environmental impact assessment, conducted long before the pellets were dropped, found that the poison used to kill the rats was not expected to harm birds because the birds would have to consume a high number of rodent carcasses.

Fish and Wildlife personnel have collected tissue samples for testing so they can determine exactly why the birds died, and the results of that study should be available by the end of June.

Until then, speculation won't do any good, Woods said, and the die-off remains a mystery.

"It's really a puzzle to everyone," he said. "There's a lot of people who want to know, because it doesn't seem to make any sense at this point."

Contact Casey Grove at cgrove@ktuu.com