An article on birdlife.org titled “The Bar-tailed Godwit undertakes one of the avian world’s most extraordinary migratory journeys” is a mind-blower of the first water. Apparently, it’s been out there for over five years, but I just stumbled across it.
In dry scholarly terms, the anonymous authors lay out some extraordinary info. My favorite reference in the footnotes (my emphasis): “Piersma, T. and Gill, R. E. (1998) Guts don’t fly: small digestive organs in obese bar-tailed godwits.”
How many times do you see a title like “Guts don’t fly” on a scientific paper? We deal with both the “small digestive organs” and the “obese” issues below.
Bar-Tailed Godwit. Photo by DickDaniels (http://carolinabirds.org/) (Own work) [CC BY-SA 3.0]
Bar-tailed Godwits fly from Alaska to New Zealand in one go, not stopping for anything (this has been confirmed by satellite telemetry). They fly at 35mph for 8+ days (with the help of tail winds), totaling 6,800 miles, without stopping. Total round-trip travel over the year is 18,000 miles. On the return journey, they make one stop along the Yalu River Estuary, which forms part of the border between China and North Korea. They stay there for several weeks, stocking up on Chinese and Korean fare, no doubt. Finally, they make it from there to Alaska, a little matter of 2500 miles or so, without eating again.
Before a godwit leaves on its northern or southern journey, 50% of its body weight is fat. Now there’s a body mass index to ponder. The godwit’s gizzard and intestines shrink as it begins its long flight, to near non-existence. Men will be able to relate to shrinkage of this magnitude, having experienced the effect of a swim in cold waters.
A Bar-tailed Godwit will fly 285,000 miles in its lifetime. Black-tailed Godwits are already in a “near threatened” status because of the degradation of the wetlands in the Yalu River estuary they depend on as a rest stop, and because of the degradation of their home grounds in Alaska. Among the American breeding population, in their main feeding grounds in Western Alaska, global warming is changing the land, especially with coastal erosion and wetland drying, both cited by the US Fish & Wildlife Service as changes occurring now in western Alaska.
So if you see a Bar-tailed Godwit on the side of the road with its alulae (thumb feathers) stuck out, invite it to hop in. And don’t offer it a diet soda or turkey bacon. It really needs some fat.
Information from BirdLife International (2010): The Bar-tailed Godwit undertakes one of the avian world’s most extraordinary migratory journeys . Presented as part of the BirdLife State of the world’s birds website. Available from: http://www.birdlife.org/datazone/sowb/casestudy/22