A flash of sapphire, a flutter of wings, and the tiny bird—or was it an insect?—vanishes, the briefest mirage. Moments later it reappears, this time at a better angle. It's a bird all right, a thumb-size dervish with hyperkinetic wings that can beat 80 times a second, producing the faintest hum. Tail feathers paddle, steering gently in three dimensions. As the bird stares into the trumpet of a bright orange flower, a thread-thin tongue flickers from its needle beak. A sunbeam glances off its iridescent feathers, the reflected color as dazzling as a gemstone hung in a sunny window. Little wonder hummingbirds inspire heartfelt affection and stuttering efforts at description. Even reserved scientists can't resist such words as "beautiful," "stunning," and "exotic."
A greater wonder is that the seemingly fragile hummingbird is one of the toughest beasts in the animal kingdom. Some 330 species thrive in diverse and often brutal environments: from Alaska to Argentina; from the Arizona desert to the coast of Nova Scotia; from the lowland forests of Brazil to the 15,000-foot-plus (4,600 meters) snow line of the Andes. (Mysteriously, the birds are found only in the New World.)
"They're living at the edge of what's possible for vertebrates, and they're mastering it," says Karl Schuchmann, an ornithologist at Germany's Alexander Koenig Zoological Institute and the Brehm Fund. Schuchmann knows of a captive hummer that lived 17 years. "Imagine the durability of an organism of only five or six grams to live that long," he says. Its cranberry-size heart, which averages 500 beats a minute (while perching!), would have thumped four and a half billion times, nearly twice the total for a 70-year-old person.
Yet these little birds are durable only in life. In death their delicate, hollow bones almost never fossilize. This was one reason for the astonishment that greeted the recent discovery of a jumble of 30-million-year-old fossil bird remains that may include an ancestral hummingbird. Like modern hummers, the fossil specimens had long, slender bills and shortened upper wing bones topped by a knob that may have let them rotate in the shoulder socket for hovering flight.