A bird once thought extinct and then found only in two breeding sites in Japan has turned up on U.S. soil. Nests of the endangered Short-tailed Albatross have been discovered on two tiny islands in the northwestern Hawaiian islands. Previously the birds were only known to nest on Torishima and Senkaku islands in Japan.

The first nest, containing two eggs, was discovered on 213-acre Kure Atoll. However researchers don't know if the eggs are viable as they are being tended by two females albatrosses.

The second nest was found on Midway Atoll. A male and female are incubating a freshly-laid egg there.

Both atolls are part of the Papahānaumokuākea Marine National Monument.

The Short-tailed Albatross was once the most abundant of the North Pacific albatross species, with numbers going into the millions, according to the American Bird Conservancy. Feather hunters wiped out much of the population at the turn of the 20th century and in the late 1940s it was believed to be extinct.

Then in the 1950s ten pairs were discovered breeding on the island of Torishima in Japan. There are now 3,000 of the birds living there. However the tiny island, just 1.6 miles across, is also home to an active volcano, so one eruption could once again wipe the species out.

Because of that, for the past five years the international Short-tailed Albatross Recovery Team has been working to establish a new colony on Mukojima Island, which doesn't have a volcano.

When not breeding, the Short-tailed Albatross has a tremendous range, from the eastern coasts of Russia, Korea, China, Taiwan to the Aleutian and Hawaiian Islands. The birds have even been seen in the Pacific Northwest and as far south as California.

"It is very encouraging to see this species begin to expand and occupy its former range and even prospect potentially new breeding locations like Kure and Midway Atolls," Rob Suryan, chair of the Short-tailed Albatross Recovery Team, said in a release.

By Elizabeth Weise