Molting Bar-tailed Godwit in New Zealand
photo Phil Battley
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Populations of concern
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.
One of the goals of this project is to understand which and 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 mainly winter in New Zealand and southeast Australia, which is why we are putting satellite tags on birds in both New Zealand (in Feb 2007) and in Alaska (summer 2007).
General breeding biology
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-egg nests. 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 seeds and berries, to fuel for migration.
Migration and maps
The southward migration of baueri is perhaps the longest non-stop migration of any bird, in some cases flying over 11,000 km from Alaska to New Zealand without stopping. The northward migration appears to consist of a series of shorter distance jumps from New Zealand to Australia, to Korea/China/Japan, and then up to Far Eastern Russia where birds breeding in western Alaska probably cross to breeding grounds. It may be that these birds cover this route in two very long legs. See the tracks of our satellite tagged godwits to learn more about how these birds migrate:
http://alaska.usgs.gov/science/biology/shorebirds/barg_updates.html
Conservation status
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 low 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.
Color-bands and flags
Godwits marked in western Alaska carry alpha-numeric bands (black with white letters) with letters and numbers stamped on them. Small numbers of birds will be marked with satellite transmitters. Different color-bands and flags are used on Bar-tailed Godwits banded at various locations in Australasia (for more details see http://www.nzshorebirds.com/). If you see a marked bird, please note the date, location, and bands on the bird. Note whether bands were on right or left leg and the location of the bands on the leg. Band combos can also be reported to: Robert Gill (email rgill at usgs.gov)
