There are no more rats on Rat Island, but the massive effort to rid island, located in the Alaska Maritime National Wildlife Refuge, appears to be a bittersweet success, as a large number of gull and bald eagles were found dead recently.
The U.S. Fish and Wildlife Service collaborated in the effort with The Nature Conservancy and Island Conservation, said the 10-square-mile island showed no signs of brown Norway rats, which ran rampant there for 230 years.
Officials did find several bird species nesting, including Aleutian cackling geese, ptarmigan, peregrine falcons and black oystercatchers.
There is concern, however, because during two weeks of field monitoring on Rat Island, the survey team collected a higher-than expected number of bird carcasses.
Federal officials said biologists found 157 juvenile and 29 adult glaucous-winged gull carcasses, as well as 41 bald eagle carcasses that appear to have died in recent months. Some 75 percent of the eagle carcasses appear to be juvenile birds. The cause of death is unknown.
Several gull carcasses found initially are now at the National Wildlife Center's laboratory in Madison, Wis., and information on their cause of death is expected to be available by late June.
Eagle carcasses and tissue samples were picked up from Rat Island and were to be shipped to the same lab June 11.
It's not unusual for birds to die during the winter along the Aleutians, but the number found were cause for concern and further investigation, fish and wildlife officials said.
Field personnel are collecting additional tissue samples for study before destroying remaining bird carcasses to eliminate any possibility of ongoing risk.
Field reports indicate all bird species on the island, except eagles, are present in equal or greater numbers than were counted before the eradication began.
Although adult and juvenile eagles are still present on the island, numbers of sub-adult eagles are lower than pre-treatment totals, officials said.
"We are extremely encouraged by the results, but we can't declare victory yet," said Randy Hagenstein, executive director of The Nature Conservancy's Alaska chapter. "It is critically important to monitor the ecosystem recovery."
The multi-million dollar plan to eradicate the Norway rats from the island was nearly 100 percent funded by the Nature Conservancy and Island Conservation. It involved spreading about 60 tons of a lethal anticoagulant poison on the island. The decision to proceed with that plan was based on a federal environmental assessment of the project.
Secretary of the Interior Ken Salazar on May 7 saluted the efforts of the conservationists and the U.S. Fish and Wildlife Service with the presentation of a Partners in Conservation Award to the federal agency and conservation groups in ceremonies in Washington, D.C.
The project was considered the largest island rat eradication project in U.S. history.
"Restoring this natural habitat in Alaska will benefit at least 26 species of breeding birds, including 13 species of seabirds," Salazar said.
Before that eradication program began in 2008, brown Norway rats, which came ashore with the wreck of a Japanese sailing ship in 1780, had run rampant on Rat Island, all but annihilating thousands of birds that once built nests on island burrow and cliffs.
Hagenstein estimates there are at least a dozen more other islands in Alaska, mostly in the Aleutians, where such a program would be useful, although some islands are too big to ever get a grip on, including Unalaska and Adak.
"With this program we are looking at stepping up to progressively larger islands with an eye to eventually get to Kiska," which got rats when used as part of the military theater, in World War II, he said.
"The big challenge in the Aleutians is the logistics of deploying any effort out there and the weather once you get there," he said. "We were fortunate in finding a real good weather window last fall for Rat Island."
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