Birdsong: A Natural History

Birdsong: A Natural History by Don Stap Scribner, 2005; $24.00

Among some birds, life is an opera; among others, life is a cabaret. Eastern towhees, with a repertoire of fewer than a dozen songs, present daytime recitals of well-practiced favorites. Their performances include frequent encores, presumably lasting until the stagers tire and the birds move on to the next tune. By contrast, the male marsh wren is a seasoned crooner that plays up to his mostly female listeners with a repertoire of more than a hundred songs. He performs them one after another in rapid succession, without repeating a number. Most versatile of all is the brown thrasher, a singer's singer, which knows as many as 2,000 songs.

Birdsong, one of the most familiar and pleasing of natural phenomena, remains, for the most part, one of the most enigmatic as well. Although ornithologists have amassed vast recorded archives of glides, twitters, and warbles, little is known of the origin and function of avian musicianship. Because most of the singers are male, and because birdsong tends to peak in the spring mating season, singing probably helps to stake out good territory and--just as it does among people--to attract the opposite sex. Ornithologists also know something about how birdsong is produced. The sound comes from an organ called the syrinx, a little chamber of muscle, membrane, and cartilage, which vibrates when air is forced through it. In nearly every group of birds, different parts of the syrinx vibrate independently, enabling a bird, in effect, to sing a duet with itself: Moreover, avian hearing and perception can be remarkably acute. In one series of experiments, pigeons were able to discriminate reliably between compositions by Bach and Stravinsky.

But the most remarkable and puzzling aspect of birdsong is that many birds learn their songs from other birds--at least among the 4,500 species in a large suborder called oscines, or songbirds, a group that includes chickadees, jays, orioles, thrushes, and warblers. Other kinds of birds, such as chickens, ducks, and hawks, tend to make calls that are genetically wired in. But if you're a singing bird rather than a squawking or quacking one, chances are you learned your song from your father, uncle, or neighbor. There are, consequently, "dialects" of birdsong: variations on tinting, pitch, and pronunciation evident in distinct local populations. Black-capped chickadees in mainland New England (and in most of the U.S.) sing a two-note song that sounds like "hey! sweetie." But out on Martha's Vineyard, an island off the coast of Massachusetts, the same species sings its song with many specific variations--ranging from "sweetie, hey!" to "sosweetie-sweetie"--depending on its nesting location.

Don Stap, a professor of English at the University of Central Florida in Orlando, may not have professional credentials in animal acoustics, but he's a seasoned birder who has already published a book (A Parrot Without a Name) based on fieldwork by prominent ornithologists. He provides both a lucid overview of the major research findings about birdsong, and a running narrative about the daily lives of two ornithologists, Gregory F. Budney of Cornell University, in Ithaca, New York, and Donald E. Kroodsma, of the University of Massachusetts-Amherst. Much of the time, they just sit around listening--in the velvet fog of early morning in the Sierras, for instance, or in the dank mist of a Central American rainforest. But even to a tin-eared nonbirder like me, Stap's descriptions make the work sound exciting.

Stap has a gift for depicting exotic places. But the puzzle of birdsong by itself is an engaging one: Just what are the birds saying to one another, anyway? If their songs are learned, how did the tunes originate? And how do the songs change over time? In this digital age, a CD or DVD attached to the book might have added a useful dimension to an otherwise boffo performance. Even without audio-visual aids, though, Stap's fine book is--how shall I sum it up--a tweet!

LAURENCE A. MARSCHALL, author of The Supernova Story, is W.K.T. Sahm Professor of Physics at Gettysburg, College in Pennsylvania. He is the 2005 winner of the Education prize of the American Astronomical Society.

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