Federal wildlife biologists report another successful breeding season for the rare Laysan ducks on Midway Atoll, with 115 fledglings banded since August.

In the three years since small groups of ducks were relocated from Laysan Island, their population at the atoll has grown from 42 to 200.

The endangered Laysan duck, Anas laysanesis, is considered the rarest native waterfowl in the United States and occurs only within the Papahanaumokuakea Marine National Monument in the Northwestern Hawaiian Islands.

The ducks, also known as Laysan teals, were once widespread across the Hawaiian Islands, but by 1860, they were found only on Laysan Island, a low-lying island that is home to millions of seabirds. By the time the Laysan duck was listed as endangered in 1967, its numbers had dwindled to 300 to 500 birds.

Beginning in 2004, biologists with the U.S. Geological Survey and U.S. Fish and Wildlife Service transferred 42 wild ducks from Laysan to start a second population 750 miles away at the Midway Atoll National Wildlife Refuge. The conservation action was undertaken to increase the highly endangered duck's geographic distribution and reduce its risk of extinction from hurricanes, tsunami, avian flu, invasive species and other dangers.

"These rare, wild ducks could not coexist with rats, migrate or disperse away from Laysan Island, so a few birds were translocated by ship to restore the species to a larger range," said project coordinator and USGS wildlife researcher Michelle Reynolds in a news release. "Now Laysan ducks are found on three rat-free islands for the first time in hundreds of years and are flying between islands at Midway Atoll."

During the 2006 breeding season, the ducks produced 56 fledglings.

USGS biotechnician Jimmy Breeden reported marking approximately 115 fledgling birds with unique leg bands during the most recent breeding season from August to December. The banding effort will help the refuge staff monitor the population status next year.

With the success of the experimental program, researchers are considering establishing a third population on another predator-free island, Reynolds said.

Laysan ducks have multicolored brown feathers, a white eye ring, a bluish-green wing patch and orange legs and feet. The ducks are primarily insect feeders, but also forage for seeds.

In addition to expanding the duck population, the Midway project has allowed researchers to learn more about the species.

The first birds transported from Laysan carried small transmitters so they could be located in dense vegetation. Monitoring revealed the ducks are capable of using a variety of vegetation types for nesting and foraging that are not available on Laysan.

Researchers also were surprised to see the ducks flying between the small islands that comprise Midway Atoll.

"The outlook for the conservation of Laysan duck is more optimistic, given their ability to nest and forage in unfamiliar and non-native vegetation," Reynolds said.

The Hawaiian duck, koloa maoli (Anas wyvilliana), is the only other endemic duck species still found in Hawai'i.

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