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One of the goals of this project is to understand how the different Bar-tailed Godwit subspecies use the Pacific Basin. L. l. baueri, a major focus of this study, breeds in western Alaska from Yukon-Kuskokwim Delta up to North Slope as far east as Colville River Delta. This subspecies appears to spend the Boreal winter mainly in New Zealand and southeast Australia, which is why we are putting satellite tags on birds in both New Zealand (in Feb 2007 and 2008) and in Alaska (June 2007). In February 2008 we also began a study of the L. l. menzbieri population that nests in northeastern Siberia and spends the Boreal winter in western Australia.
In North America, this large (males 250-350 g, females 300-500g) shorebird is only commonly found in western and northern Alaska during the summer (where it breeds) and fall. In fall, it stages in spectacular concentrations along the coast of the Yukon-Kukskokwim Delta and further south on the Alaska Peninsula before departing on the longest non-stop migration known for any shorebird species, across the Pacific Ocean down to New Zealand and southeast Australia.
Up to five subspecies of Bar-tailed Godwits (Limosa lapponica) are recognized, breeding from northern Norway to western and northern Alaska.
Bar-tailed Godwits breed in open tundra, usually in better drained areas, but sometimes in wet basins and other poorly drained areas. They form a cup nest on the tundra and almost always lay 4 eggs. Young hatch after 20-21 days and are almost immediately mobile. Chicks can fly at about 29 days, and soon after that parents leave the chicks. Both young and adult birds move from nesting areas to staging sites along the coast of Alaska to fatten for their open-ocean, non-stop migration to Australasia. Birds form large flocks along the Alaska coast in the late summer and fall, feeding mainly on clams and worms, but also on seeds and berries to fuel their flights.
The southward migration of baueri is the longest non-stop migration of any bird, in some cases birds are flying over 11,000 km from Alaska to New Zealand without stopping. The northward migration of baueri occurs in two long flights, the first from New Zealand and eastern Australia to the Yellow Sea and the second from there to Alaska. We hope to learn more about the northward flight of menzbieri, but it too is known to at least stop in the Yellow Sea. Much less is known about its southward migration, particularly once the birds leave the breeding grounds in Siberia.
It is estimated that 100,000-150,000 Bar-tailed Godwits breed in Alaska. Under the US Shorebird Conservation Plan, they are a species of High Concern mainly due to their small population size, threats to their non-breeding grounds (especially at migratory stopover sites in Asia), and their relatively restricted breeding distribution within the United States.
Text courtesy of PRBO
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