Robert Krulwich has a great post on the Bar-tailed Godwit.
They are the only birds known to fly more than 7,000 miles nonstop, that means no food breaks, no water breaks, no sleep breaks, no pausing, just pushing through cyclones, storms, headwinds, flappity flap, flap for days and nights- and this is their championship season. In September and October, they leave Alaska, head straight for the ocean. Though they are land birds, and cannot fish or rest on the sea, they will cross most of the Pacific Ocean, and fly all the way to New Zealand. Many of them are young, and have never done this before.
Every year, between August and November, these birds wait for the cyclonic storms that generate favourable wind for southward departure. “Once they hit mid-passage, equatorial breezes slow and the bird has to beat his or her way south without much help. They burn half their body weight as they fly, and sleep, bird-style, by shutting down one side of the brain at a time. Past the equator, they bump into the southeasterly trade, which is the runner's equivalent of an uphill slog, pushing them west, so they have to navigate to keep on course.”
What an amazing feat! Why does this bird do this long-distance flying non-stop? What is the purpose of this whole exercise? A comment on the article explains “ If it is accustomed to a diet of a certain type and surroundings of a certain temperature and form that is nearly polar, it is unlikely to achieve this other than by traveling to nearly the opposite pole”.
What a tough little bird!