Tuesday, May 25, 2010

Avian athletes who start their marathons with bodies that are 55 percent fat

A human whose body was 55 percent fat would suffer from crippling obesity. For the bar-tailed godwit, it just means it's ready to go, looking like a softball with wings.

The godwit is a land bird that summers in Alaska and winters in the South Pacific. Its migration is a 7,100-mile, nine-day nonstop flight at a steady 40 miles per hour. Because it feeds on land, it can't stop to eat along its open-water route. Instead, it kicks its metabolism into high gear and burns all that fat.
Consider what might be the ultimate test of human endurance in sports, the Tour de France: Every day, bicyclists pedal up and down mountains for hours. In the process, they raise their metabolism to about five times their resting rate.

The bar-tailed godwit, by contrast, elevates its metabolic rate between 8 and 10 times. And instead of ending each day with a big dinner and a good night’s rest, the birds fly through the night, slowly starving themselves as they travel 40 miles an hour.
Today's NYT Science Times has a fascinating story about what new tracking technology is telling scientists about long-range bird migrations. It turns out that a lot of birds they thought had to migrate mostly by land in order to feed actually make vast nonstop flight over open water. This includes birds as small as the hummingbird.
Not long ago, ornithologists had far lower expectations for birds. Ruby-throated hummingbirds, for example, were known to spend winters in Central America and head to the United States for the summer. But ornithologists believed that the hummingbirds burned so much fuel flapping their wings that they simply could not survive a nonstop trip across the Gulf of Mexico. They were thought to have flown over Mexico, making stops to refuel.

In fact, ruby-throated hummingbirds returning north in the spring will set out from the Yucat√°n Peninsula in the evening and arrive in the southern United States the next afternoon.
Almost makes running 26 miles and 385 yards seem pedestrian in comparison.

1 comment:

Leslie F. Miller said...

I'm getting ready to do three miles with 24% body fat. Yikes.