Arctic foxes steal thousands of waterfowl eggs and cache them under the tundra for lean times. Wildlife managers want to protect eggs of the Pacific black brant, whose numbers have been declining steadily.
All-terrain vehicles that disturb coastal nests are partly to blame, as are increased fall floods and hunters who take several thousand brant every year, according to managers.
Foxes in the refuge in 400 miles west of Anchorage may be the biggest reason black brant numbers are only about two-thirds what they were in 1960, managers said. Most of the world's 115,000 black brant gather each summer on the marshy plain in several nesting colonies.
Hunters in Canada, Mexico and the U.S. take about 14,000 black brant a year, said Tom Rothe, waterfowl coordinator for the state Department of Fish and Game. Native subsistence hunters on the delta take about 4,000 of those.
"We make soup out of it," said Anthony Boyscout of Chevak, a village in the 19 million-acre refuge.
A single fox will swipe several hundred eggs in a matter of weeks if it can't find tundra mammals to eat. The foxes frighten away weak birds on the edges of colonies, then grip the large eggs in their mouths and ferry them to nearby burrows.
"They'll just keep coming and coming," Rothe said.
State and federal wildlife managers are reducing the foxes as part of a $100,000, five-year study initiated this year by the U.S. Geological Survey, said research associate and wildlife biologist Michael Anthony.
In March, biologists killed about 20 foxes using spring-loaded traps that snap shut around necks, Anthony said. Biologists hope the fox killings will protect a sample colony of about 4,000 brant that nest at the mouth of the Tutakoke River, he said.
About 50 foxes were removed from the refuge during a four-year period in the mid-1980s, he said. Brant reproduction rates jumped from less than 10 percent to more than 80 percent, he said.
The program was not continued and brant numbers began falling again in the 1990s, he said.
The research aims to help create a model that predicts when foxes are likely to raid nests and when they should be eradicated, he said. The study also will gather information to help scientists estimate vole numbers, which figure into determining the number of foxes, he said.
One question is whether increasing fall floods are killing foxes and voles, he said.
Bethel-based refuge manager Mike Rearden said a fall storm last year, the biggest in memory, sent saltwater at least 10 miles inland. The storm, fueled by rising global temperatures, may have killed thousands of voles and some foxes, he said.
State and federal managers from California to Alaska have been trying to protect brant for years, Rothe said. They hope to bring their numbers to 1960 levels of about 150,000, he said.
Recreational hunting seasons were halved last year in four states, including Alaska, to protect the bird. The fall season on the Alaska Peninsula, which begins Sept. 1, now lasts just a month, he said.
Federal regulations also will reduce subsistence hunting on the delta beginning this year, he said.
The Native village corporation in Hooper Bay, north of the Tutakoke River, restricted ATVs from traveling on corporation land near a large colony last year, said Myron Naneng, a member of the Alaska Migratory Bird Co-Management Council, which recommends subsistence harvests in Alaska.
In part because of those efforts, the number of nesting pairs jumped from 1,000 in 2004 to 4,000 last year, Naneng said.
The limitations are important, said Richard Tuluk, tribal administrator in Chevak.
"We need to use these resources for our dinner tables and to provide nutrition for the young ones," he said.