Tuesday, June 25, 2013
For The Birds
Birds did it long before humans, and they still do it better
Once, many years ago on a delivery flight in a Cessna 207 to Buenos Aires, Argentina, I followed a Condor around a thermal and rode the free lift to 13,000 feet, while he watched my comparatively ugly machine struggling to match his moves. Without his (her?) guidance, the overloaded Cessna never would have made it across the ridge from Chile to Argentina.
Climbers spot Condors regularly at elevations of 20,000 feet in South America, and a Lan Chile airline crew once reported seeing one of the giant, 10-foot wingspan birds soaring by at 32,000 feet above Cerro Aconcagua, the highest mountain in South America. Standard temperature at 32,000 feet is -44 degrees C.
As one who has a little experience flying long distances, I was especially interested in the bird investigations of Robert Gill, a wildlife biologist for the U.S. Geological Survey Science Center, who was working with migratory birds. In the 1980s, Gill noticed that a small Alaskan wading bird, the bar-tailed godwit, nearly doubled its body weight in preparation for the fall migration to New Zealand. Gill said the birds became so fat, he wondered how they could fly at all.
At the time, Gill was frustrated with his inability to track the godwits, but he believed they had to land many times on Pacific atolls during their migration south. By 2006, technology finally caught up with Gill, offering him a solution in the form of an incredibly light, one-ounce GPS tracking device. Gill transplanted the trackers into several godwits in Alaska, then monitored the GPS readout.
The birds waited for favorable winds that blow south above the Gulf of Alaska every fall. Gill monitored his test subjects electronically, as the birds waited for just the right moment, then lifted off and flew straight south down the center of the Pacific.
Many of them tracked directly to New Zealand, 7,100 miles nonstop in nine days. They made no stops on islands or ocean for anything—food, water, rest or sleep. The godwits slept bird-style by shutting down half their brain at a time while they continued to flap toward New Zealand at a steady 35 mph. Gill contacted wildlife officials in New Zealand who told him many of the birds landed after their epic flights and immediately collapsed from exhaustion, having worked off all the weight they'd put on in Alaska.
Perhaps equally amazing, some of the godwits return to the same locations every year, often touching down within a half-mile of the previous year's destination.
No one has any idea how migratory birds navigate, although some speculate it may be a function of somehow analyzing the Earth's magnetic field. Others theorize it may be a form of avian celestial navigation. That's unlikely since birds on their first trip south would never have seen stars in the southern hemisphere. Perhaps they simply follow their leaders.
And perhaps birds, born to the sky, are created with something mere humans will never understand—a natural sense of flight. They need not study or analyze the ability to do what they do. They're born understanding. In the words of Richard Bach, writer, dreamer, poet, philosopher, pilot and perhaps part bird himself, from his novel/instruction manual on pure flight, Jonathan Livingston Seagull, "Don't believe what your eyes are telling you. All they show is limitations. Look with your understanding. Find out what you already know, and you'll see the way to fly."
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