Contrasting extreme long-distance migration patterns in bar-tailed godwits <i>Limosa lapponica</i>

Migrating birds make the longest non-stop endurance flights in the animal kingdom. Satellite technology is now providingdirect evidence on the lengths and durations of these flights and associated staging episodes for individual birds. Using thistechnology, we compared the migration performance of two subspecies of bar-tailed godwit Limosa lapponica travellingbetween non-breeding grounds in New Zealand (subspecies baueri) and northwest Australia (subspecies menzbieri) andbreeding grounds in Alaska and eastern Russia, respectively. Individuals of both subspecies made long, usually non-stop,flights from non-breeding grounds to coastal staging grounds in the Yellow Sea region of East Asia (average 10 060 ? SD290 km for baueri and 5860 ? 240 km for menzbieri). After an average stay of 41.2 ? 4.8 d, baueri flew over the North PacificOcean before heading northeast to the Alaskan breeding grounds (6770 ? 800 km). Menzbieri staged for 38.4 ? 2.5 d,and flew over land and sea northeast to high arctic Russia (4170 ? 370 km). The post-breeding journey for baueri involvedseveral weeks of staging in southwest Alaska followed by non-stop flights across the Pacific Ocean to New Zealand (11 690 kmin a complete track) or stopovers on islands in the southwestern Pacific en route to New Zealand and eastern Australia. Bycontrast, menzbieri returned to Australia via stopovers in the New Siberian Islands, Russia, and back at the Yellow Sea; birdstravelled on average 4510 ? 360 km from Russia to the Yellow Sea, staged there for 40.8 ? 5.6 d, and then flew another5680–7180 km to Australia (10 820 ? 300 km in total). Overall, the entire migration of the single baueri godwit with afully completed return track totalled 29 280 km and involved 20 d of major migratory flight over a round-trip journey of174 d. The entire migrations of menzbieri averaged 21 940 ? 570 km, including 14 d of major migratory flights out of 154 dtotal. Godwits of both populations exhibit extreme flight performance, and baueri makes the longest (southbound) andsecond-longest (northbound) non-stop migratory flights documented for any bird. Both subspecies essentially make singlestops when moving between non-breeding and breeding sites in opposite hemispheres. This reinforces the critical importanceof the intertidal habitats used by fuelling godwits in Australasia, the Yellow Sea, and Alaska