Preface

The earth has music for those who listen.
    --William Shakespeare

Somewhere, always, the sun is rising, and somewhere, always, the birds are singing. As spring and summer oscillate between northern and southern hemispheres, so, too, does this singing planet pour forth, like a giant player piano, in the north, then the south, and back again, as it has now for the 150 million years since the first birds appeared.

Ten thousand species strong, their voices and styles are as diverse as they are delightful. Some species learn their songs, just as we humans learn to speak, but others seem to leave nothing to chance, encoding the details of songs in nucleotide sequences in the DNA. Of those that learn, some do so only early in life, some throughout life; some from fathers, some from eventual neighbors after leaving home; some only from their own kind, some mimicking other species as well. Some species sing in dialects, others not. It is mostly he who sings, but she sometimes does, too. Some songs are proclaimed from the treetops, others whispered in the bushes; some ramble for minutes on end, others being offered in just a split second. Some birds have thousands of songs, some only one, and some even none. Some sing all day, some all night. Some are pleasing to our ears, and some not.

It is this diversity that I celebrate. How the sounds of these species differ from each other is the first step to appreciating them, of course, but those questions quickly give way to "why" questions. Why do some learn and others not? Why do dialects occur in some species and not others? Why is it mainly he who sings? It is these and similar why questions that so intrigue us biologists as we try to understand the individual voices that contribute to the avian chorus.

In writing about our singing planet, I can focus on only a few of our planet's voices. The thirty stories told here are personal journeys, ones that I have traveled over the past 30 years in my quest to understand the singing bird. Many are based on my own research and are years in the making. Others are based on just several days' experience, or even less, as I seek out birds that illustrate the research of friends and colleagues who share my passions. No matter the source, each story is based on listening and on learning how to hear an individual bird use its sounds, and each story illustrates some of the fundamentals of the science called "avian bioacoustics." Together, I hope these stories and their sounds reveal how to listen, the meaning in the music, and why we should care.