By Tina Mitchell
Water hopscotching over rocks in a creek bed. Leaves crackling underfoot. A squirrel chatter-scolding as you walk past its tree. The slap of a beaver tail as its owner disappears under water while you move past its pond. The wind howling and swirling the new-fallen snow. Music in nature takes many forms, many tones, many timbres. But the featured artists in Nature’s symphony are the avian maestros. Birds have the greatest sound-producing capabilities of all vertebrates, generating songs that penetrate dense cover and carry long distances. Moreover, the vocal repertoires of birds rank among the richest and most varied of any in the animal kingdom. How do birds make such complex music?