the remarkable power and fragility of hummingbirds -- 6/08/16

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Today's selection -- from Birdology by Sy Montgomery. The exquisitely delicate hummingbird is the lightest bird in the sky, but is in some respects the most powerful. One species of hummingbird can dive at a rate of sixty-one miles per hour.

"Unlike our thick, marrow-filled bones, most birds' bones are hollow. Even their skulls are scaffolded with passageways for air. Their feather shafts are hollow, and the feathers themselves, like strips of Velcro, are interlocking barbules for catching air. Their bodies are filled with air sacs, which originate in, and function, in part, as extensions of the lungs. No fewer than nine of these filmy bladders fill the tiny body of a hummingbird: one pair in the chest cavity; another under each shoulder blade; another pair in the abdo­men; one under each wing; and one along the neck.

A female ruby-throated humming bird hovering in mid-air

"Hummingbirds are the lightest birds in the sky. Of their roughly 240 spe­cies, all confined to the Western Hemisphere, the largest, an Andean 'giant,' is only eight inches long; the smallest, the bee hummingbird of Cuba, is just over two inches long and weighs a single gram.

"Delicacy is the trade-off that hummingbirds have made for their unri­valed powers of flight. Alone among birds, they can hover, fly backward, even fly upside down. For such small birds, their speed is astonishing: in his courtship display to impress a female, a male Allen's hummingbird, for instance, can dive out of the sky reaching sixty-one miles per hour, plung­ing from fifty feet at a rate of more than sixty feet per second -- and pulling out of his plunge, he experiences more than nine times the force of gravity. (Adjusted for body length, the Allen's is the fastest bird in the world. Diving at 385 body lengths per second, this hummer beats the peregrine falcon's dives at 200 body lengths per second -- and even bests the space shuttle as it screams down through the atmosphere at 207 body lengths per second.)

Rufous hummingbird

"Hummingbirds' wings beat at a rate that makes them a blur to human eyes, more than sixty times a second. For centuries, people deemed hum­mingbird flight pure magic. Until the invention of the stroboscope, scien­tists could not understand how hummingbirds hover. With a flash duration of one hundred-thousandth of a second, the stroboscope finally revealed the motion of wings that had been too fast for other cameras to capture.

author:	Sy Montgomery
title:	Birdology: Adventures with Hip Hop Parrots, Cantankerous Cassowaries, Crabby Crows, Peripatetic Pigeons, Hens, Hawks, and Hummingbirds
publisher:	Free Press a division of Simon and Schuster
date:	Copyright 2010 by Sy Montgomery
pages:	78,79, 90