Sjhaana Clovoc, via e-mail

Avian hearing has been famously credited with alerting humans to impending danger. During World War I parrots kept on the Eiffel Tower warned citizens of approaching aircraft, and centuries earlier Rome was reputedly saved by a gaggle of cackling geese. Even today birds are employed as barnyard "watchdogs." What is audible to them clearly affects their survival, sometimes from very early on. Some species can vocalize before they hatch, and the hearts of young song sparrows beat faster upon hearing their species' song for the first time. Many birds can identify mates or other group members by voice alone. One study found that the male mockingbirds with the largest repertoires not only get the best territories but also attract mates more readily. To be sure, several species weigh in as aural virtuosos: Owls can home in on prey when it's too dark to see. Woodpeckers can pinpoint beetle larvae munching inside a tree. Swiftlets and oilbirds can navigate dark caves by echolocation. But on the whole, birds hear within the same general frequency range as we do. Their ears, located behind their eyes, are inconspicuous because they don't have external pinnae (as we do) and are covered by protective auricular feathers. In structure, the avian hearing organ is remarkably similar to that of reptiles, reflecting birds' emergence from dinosaurs, ages before they were enlisted to stand vigil for mankind.

David J. Krasovic, Rocky River, Ohio

The prickly, skin-puckering sensation you experience when you're frightened or titillated or shivering from the cold is caused by constriction of tiny arrector pili muscles at the base of the hairs on your arms, your legs, and the back of your neck. Technically known as piloerection--pil is Latin for "hair"--goose bumps are a holdover from long ago when our hairier forebears hunted mastodons. Your body is attempting to stay warm by "fluffing out" your nonexistent fur. In the old days, chilly weather made the voluminous hair of primordial hominids bristle, providing natural insulation by creating pockets of warmer air between the skin and the outside cold. Piloerection is one of those rudiments, like the vestigial tailbone, that Darwinists believe will disappear over evolutionary time. Piloerection also plumps up mammals' coats, and yes, says Louisiana State University biologist Mark Hafner, it underlies puffing-up defense behavior. The latter is "probably a secondary function," he says, "because not all mammals show it. But there's no doubt that piloerection makes an animal appear larger, which may cause a potential competitor or predator to look elsewhere for a smaller and less imposing victim." 

How do insects avoid getting hammered by raindrops?

Judith Templeton, New York, New York

With roughly 750,000 known insect species and millions more yet to be discovered, rest assured that there is plenty of diversity in their acclimation to wet weather. Entomologist John Pickering, who has studied the invertebrates in Central and South American rainforests, where it rains a lot (annual precipitation in rainforests can exceed 200 inches), thinks most terrestrial arthropods probably do what we do--seek shelter. During a storm they can often be found hunkered down in protected areas in trees, rocks, crevices, and manmade structures. Of course, not all bugs will survive a downpour, but those that do just dry themselves off and pick up where they were splashed off (remember the itsy-bitsy spider?). Pickering says that some of the best adaptations he has come across involve social insects. "In Panama, paper wasps dry out their nests after a heavy rain by sucking water off the casing and then spitting it over the side. Other wasp species build drip-tips on the outside of their nests that help divert water away from the brood. In Brazil, I've seen spectacular termite nests that are larger on top than at the base--the top presumably serves as an umbrella." Fire ants have a truly resourceful approach to seasonal flooding in South America: "They ball up as a colony and float to safety," Pickering says. As part of the life-and-death drama of the animal kingdom, rain is sometimes a boon or a bust to a population. Witness the swarms of mosquitoes or the exodus of earthworms brought forth by a spring shower. 
 
 

By Carolyn Shea

Illustrations by Jonathan Carlson
www.theispot.com/artist/jcarlson