The bar-tailed godwit makes the longest nonstop migration of any bird in the world, flying 11,000 kilometers from Alaska to New Zealand every autumn. But that is just one reason to laud this bird. The bar-tailed godwit also, say scientists, is savvy enough to adapt to the changing circumstances resulting from climate change.
Every autumn, the bar-tailed godwit — who appear to be indistinctive brown, black and gray waders — makes an eight day journey that begins in Alaska and ends in New Zealand. It is a flight that surpasses what any human-made aircraft can do. The bar-tailed godwit does not stop once to eat or rest for those 11,000 kilometers south. Come spring, it repeats the same extraordinary journey, flying from the tropical, temperate zones of New Zealand over the Pacific Ocean to Alaska.
To do this, the birds detect when storm systems arise as they rely on their powerful wind gusts to move at speeds of about 35 miles an hour. About midway in their journey south, the breezes slow. The birds use up about half their body weight to fly the rest the way, sleeping “bird-style, by shutting down one side of the brain at a time,” as NPR puts it.
Scientists have been fearing how the bar-tailed godwit and other migratory birds will fare as climate change affects atmospheric conditions. Computer models have predicted that wind currents are likely to change as a result of global warming. The bar-tailed godwit relies on tailwinds from the backsides of low-pressure systems that pass across the northern Pacific; in the future, these systems are likely to occur more to the north so that the average “net tailwind index” (as scientists call it) will “show some degradation.”
David Douglas, a wildlife biologist with the United States Geological Survey in Anchorage, says that the bar-tailed godwit seems to be able to access weather conditions and alter when they migrate. The birds are then able ”to pick times when the atmospheric conditions are favorable for the journey to New Zealand – when there are good tailwinds.” As Douglas explains, the birds “don’t depart on random” but are “very good at cuing in on when the conditions are just right.”
The bar-tailed godwit faces other obstacles to its survival. The godwits’ population has declined in recent years. Once 100,000 birds descended on New Zealand in the summer, but this number has fallen to 70,000. Similar declines have been noted throughout the birds’ East Asian and Australasian flyways; up to 85 percent of their shorebird populations are declining as a result of the reclamation of their feeding grounds in tidal mud flats in South Korea and China and of geographical changes from projects such China’s Three Gorges Dam.
To survive in a world changed by global warming, altering our habits is necessary. For the bar-tailed godwit, that means adjusting when it catches the winds that help it makes it day-long migration. For us, that means changing our habits and not just seeking out, but implementing sustainable alternatives for energy and for reducing our carbon footprint. The bar-tailed godwit can fly far and for days on end, but it can’t direct what happens on land. That’s up to us to work on.
Photo from Thinkstock