A Century Later, Millerbirds Return to Laysan Island

by Holly Freifeld, Sheldon Plentovich, Chris Farmer, and George Wallace

After more than a week trapped indoors by high winds and driving rain on Laysan Island, Robby Kohley and Cameron Rutt, biologists with the Millerbird Translocation Project, were eager to get back outside. They set off to check on the endangered Nihoa Millerbirds (Acrocephalus familiaris kingi) translocated to Laysan – one of the Northwestern Hawaiian Islands – last September from Nihoa Island, which lies 650 miles (1,046 kilometers) to the southeast. Last they knew, several pairs were building nests and one pair was incubating a clutch of two eggs. After several hours of patient observation, Kohley and Rutt were amply rewarded: a pair of Millerbirds was brooding and feeding a nestling—the first of 2012, and soon to be the first Millerbird to fledge on Laysan in nearly a century.

The Hawaiian Islands have lost a number of species as a result of human activities since the late 1800s. Laysan Island alone has lost three bird species, including the Laysan Millerbird (Acrocephalus familiaris familiaris), which vanished in the early 1920s following the destruction of this island's vegetation by introduced rabbits and other livestock. In September 2011, a team of 12 biologists led by the U.S. Fish and Wildlife Service (Service) and American Bird Conservancy set out on an expedition to tiny Nihoa Island, where the single remaining population of Millerbirds persists. Twenty-four Millerbirds were captured and transported three days by sea to Layson Island—the first Millerbirds to inhabit the island in almost 100 years.

Kohley and Rutt remained on Laysan following the release to monitor the birds through the fall and winter. This first-ever opportunity to observe Millerbird behavior and ecology year-round, including the full breeding cycle, is a significant advance in the study of this rare bird. Within weeks of their release last fall, males were singing and both sexes were defending territories. The birds soon began to pair up, and the first birds carrying nesting material were observed in early October. Although those initial nesting efforts &ndahsh; 10 nests; three with eggs and one with nestlings – were ultimately unsuccessful, they were exciting and encouraging. The Millerbirds are acclimating rapidly to their new home. The Millerbirds have ranged greater distances on Laysan than ever observed on Nihoa. One bird made multiple trips to the south end of the island, more than a mile away. However, most birds settled down in the vicinity of release sites in the northern part of the island. Currently, 21 birds are known to have survived the winter, but given their cryptic, skulking nature, the three missing birds may have escaped detection.

The first nest-building activity of 2012 was spotted on Valentine's Day. As of the most recent report from the island, one pair of Millerbirds is feeding a fledgling, another pair is feeding a nestling, and two pairs are incubating eggs. Four more pairs are nest-building, and two more may follow suit. The project team and recovery partners now wait anxiously for more Millerbird chicks to fledge on Laysan. The first successful nests are a major milestone in the project, but a self-sustaining Millerbird population is a long way off. A second translocation is planned to ensure a solid foundation for this nascent population; this effort may take place in 2012, funds permitting. The establishment of a self-sustaining Millerbird population on Laysan will re-create a lost ecological connection on Laysan Island as well as decrease the species' risk of extinction.

Translocation has been used successfully to create new populations of many imperiled island birds, including Laysan ducks (Anas laysanensis) now thriving at Midway Atoll National Wildlife Refuge. Small, insectivorous passerines pose much greater challenges for captive management, feeding, and veterinary care. This first Millerbird translocation is the culmination of more than five years of research and field work involving more than a dozen partners. The project provides a model of collaborative planning and funding and on-the-ground teamwork for restoration of other endangered birds and island ecosystems.

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Holly Freifeld, a biologist with the Division of Migratory Birds and Habitat Programs in the Pacific Islands Fish and Wildlife Office, can be reached at holly_freifeld@fws.gov or 503-231-2015. Sheldon Plentovich, the Pacific Islands Coastal Program Coordinator in the Service's Pacific Islands Fish and Wildlife Office, can be reached at sheldon_plentovich@fws.gov or 808-792-9400. Chris Farmer, the American Bird Conservancy's Science Coordinator for Reintroduction of Hawaiian Birds, can be reached at cfarmer@abcbirds.org or 808-987-1779. George Wallace, the American Bird Conservancy's Vice President for Oceans and Islands, can be reached at gwallace@abcbirds.org or 540-253-5780, ext. 101.

Editor's note: The authors of this article were honored earlier this year by the Service as Recovery Champions for their work with the Nihoa Millerbird. For more information about the Nihoa millerbird translocation project, including the Laysan blog and links to news releases, photos, and video clips from the translocation, visit the Service's project page and Flickr site.