If the egg hatches in the middle of next month, the island might become the third breeding ground for the birds.

TOKYO — An endangered short-tailed albatross has laid an egg for the first time on Eastern Island, the U.S. Fish and Wildlife Service has announced.

If the egg hatches in the middle of next month, the island might become the third breeding ground for the birds, joining Tokyo's Torishima island, part of the Izu Islands, and the Senkaku Islands.

Eastern Island is part of Midway Atoll, about 2,200 kilometers northwest of Honolulu and about 4,000 kilometers east of Torishima island. Off-limits to the general public, it is administered by the USFWS as a nature reserve.

The mother and father bird have been taking turns warming the egg. Their leg rings show both birds were born on Torishima island, and that the male left his birth nest in 1987 and the female left hers in 2003.

The Oceanic Wildlife Society, a Japanese nonprofit organization that protects mainly marine wildlife, and other entities placed 16 decoys on Midway Atoll in 2000 to help the birds form a new colony.

Environmentalists have been trying to get the albatrosses there to form pairs by putting out the elaborately made models of the birds, and playing bird cries recorded on Torishima island.

Short-tailed albatrosses were once thought to have become extinct between the late 19th and early 20th centuries, as a result of overhunting for their feathers. However, in 1951, the birds were confirmed to be breeding on Torishima island and efforts have been made to protect them ever since. Although their numbers are gradually increasing, the birds' population is still estimated at only about 3,000.