By Jim Collins
Do birds ever fall from the sky in midflight?
—Brad Herring, Coclé, Panama
This from the strange sightings department: Every spring, cedar waxwings get drunk on fermented holly berries on Hilton Head Island, South Carolina, and crash dizzily into cars and windows. And last winter, coots, mallards, and ruddy ducks, tricked by a mild autumn into sticking around Buffalo, New York, longer than they should have, got caught in a
severe winter storm and plummeted to the ground. As far back as 1485, citizens of Augsberg, Germany, reported birds falling like rain; the creatures had apparently become disoriented by a solar eclipse. But your own chances of seeing raining birds are slim, according to Frank Gill, author of the textbook Ornithology and
director of science at the National Audubon Society, largely because they're such impressive flying machines. Consider the redfooted falcon, which weighs six ounces, has a nine-inch wingspan, and can fly 2,500 miles at a stretch. An F-16 fighter jet has a 33-foot wingspan and weighs 48,000 pounds—carrying 3,000 times more weight per inch of wing than
the falcon—and has to refuel every 600 miles.When migrating birds do run into disasters such as unrelenting headwinds or bad weather, they tend to meet their doom far out at sea. But, like all living creatures, birds are fallible even without the storms and transoceanic journeys. "They're vertebrates too," explains Gill, "so they suffer from strokes,
heart attacks, and overheating—all the frailties the rest of us do."
Recently your magazine dared me to bicycle up the 8 percent grade of the Tour de France's Alpe d'Huez. But 8 percent just doesn't sound that steep. What am I missing?
—David Cohen, Cleveland, Ohio
True, the infamous ten-mile climb up l'Alpe d'Huez (or the upcoming Tour's toughest climb, a grueling 8.5 percent grade on Montée d'Hautacam) would be a bunny slope on any self-respecting ski resort, where a decent black diamond's grade ranges from 45 to 55 percent. But a few glute-burning hours of alpine biking will wipe the sneer off any
downhiller's face: A ten-mile pedal at an 8 percent grade rises nearly 4,200 vertical feet—about a thousand feet more than the distance from Camp IV on Everest's south face to the summit. A road's grade is calculated by its vertical rise over 100 feet; an 8 percent slope rises eight feet for every 100 traveled. Still think that sounds wimpy? Consider
taking on Baldwin Street in Dunedin, New Zealand, the steepest street in the world at a 35 percent grade. The short stretch of vertiginous pavement rises one foot for every 2.86 feet.
Why do mosquitoes seem to be more attracted to some people than others?
—Jeff Adams, Portland, Oregon
Manliness is one big come-on to female mosquitoes—the ones that do the blood-sucking. A hungry mosquito prefers men to women, adults to children, and dark over light-colored clothing. And then the chemistry must be right. Here's how a mosquito chooses its victim out of a menu of campers: At long range—up to 120 feet away—it is attracted
to movement. The extrovert who stands up and delivers a ghost story arouses the pest's sensors, and it moves in. Once it reaches the campground, it switches to chemical detection: Of the hundreds of chemicals emitted by humans, carbon dioxide and lactic acid most arouse a mosquito. The bigger you are, and the more you exert yourself, the more you produce of
both chemicals; he who chops wood before dinner smells more delectable than he who stays in camp to mix the Tang. Once in close range, the skeeter makes a final selection by the moistness of its entrée—the sweatiest camper is most likely to get bitten. So can you save your skin by keeping perfectly still? Not necessarily, say entomologists, who
believe that there will be plenty of mosquitoes for everybody to swat this year. If predictions of a temperate winter hold true, a greater than normal number of eggs will survive and hatch into swarms of mosquitoes ready to home in on red-blooded victims like you.
Why are rainbows in the shape of an arch?
—Danny Frieden, Tucson, Arizona
Rainbows form when two conditions come together: sunshine at your back and rain in front of you. When that seven-color arch soars, what you're seeing is sunlight reflected from the back walls of thousands of individual water droplets at angles that your eyes pick up as color (40 degrees for blue, 42 for red). These angles get repeated in raindrops all
around you, from the left of your shadow to the right of it, so that when you're lucky enough to spot a rainbow, your shadow will point to the highest part. But that bow is just half of the potential show. Climb high enough—onto the 20,320-foot summit of Mount McKinley, say—with the sun at your back and a rainstorm ahead of you, and a rainbow
will appear as a full circle. The same phenomenon that creates the arch—the reflections at 40-some-degree angles from the back walls of the raindrops—occurs at a full 360 degrees around your shadow, not only to your left and right, but below you as well. Which may explain why you've never found that pot of gold. After all, a circle has no end.
Illustrations: Jason Schneider
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