Mice attacking Midway albatross prompt plan

Suddenly predatory mice are attacking nesting albatross on Midway Atoll – the largest albatross colony in the world — prompting a plan by the U.S. Fish and Wildlife Service to remove the “house mouse” population using rodenticide and trapping.

Midway Atoll, 1,200 miles northwest of Honolulu, is home to more than 3 million seabirds, including the world’s largest colonies of Laysan and black-footed albatross.

Mice are omnivores — meaning they will eat anything — and have been on Midway Atoll for decades. But there had never been a documented case of mice predation on adult albatross before the 2015 hatching season, Fish and Wildlife said in a news release.

Mice started attacking adult albatross as they sat on their nests — basically eating the birds alive, Fish and Wildlife said. The nesting birds are vulnerable because they refuse to abandon an egg.

“This was something we had never expected to occur. Mice preying on adult albatrosses simply hasn’t been recorded here,” Matt Brown, superintendent for the Fish and Wildlife Service in Papa­hanaumokuakea Marine National Monument, said in the release. “Regardless of what caused them to start this behavior, it has the potential to cause an incredible amount of damage to this colony.”

In just a few years, mice attacks “have increased from just a few incidents to hundreds of widespread attacks on albatross that result in injury, nest abandonment and death,” the federal agency said.

House mice and black rats became established on Midway’s Sand Island more than 75 years ago before it was a refuge and memorial. House mice remained after black rats were eradicated in 1996, according to the agency.

A draft environmental assessment for the project is available for public comment until April 20.

The service is proposing multiple applications of the rodenticide Brodifacoum 25D by helicopter on Sand Island.

“Bait will not be aerially broadcast near the beaches or marine environment on Sand Island, minimizing the chance that it enters into the ocean or impacts marine species,” a project overview states.

In areas of human occupation, on the airfield, and along sections of the coastal fringe, alternate methods are being considered including spreading the bait by hand, using bait boxes, and mechanical trapping, Fish and Wildlife said.

Within Papahanau­mokuakea, Midway Atoll National Wildlife Refuge and Battle of Midway National Memorial support over 3 million birds from 30 different species, the service said. Nearly 40 percent of all Black-footed albatross and 70 percent of all Laysan albatross in the world rely on the approximately 1,500 acres of islands that comprise the atoll.

The refuge and memorial are managed by the Fish and Wildlife Service.

A trio of aerial rodenticides was dropped on tiny Lehua Island last August and September by the Department of Land and Natural Resources to eradicate invasive Pacific rats harmful to native seabirds.

The use of the rodenticide diphacinone, in cylinder-shaped pellets, sparked community concerns over whether it would impact marine life and the environment on and around the 284-acre island off Niihau.