Since at least 1974, biologists have known that some male bats sing very much as songbirds do, and they warble for the same reasons: to defend territories and to attract mates. Recently, researchers have discovered that the tunes of some bats are even more complex and similar to bird song than first suspected. These bats’ melodies are structured, have multiple syllables, phrases, repeated patterns, and, of course, rhythm. Their songs also have syntax, meaning rules for how the phrases can be combined. But the rules are flexible, and a bat can improvise, singing a song his way. So far, scientists have identified 20 species of bat troubadours around the world. Here are some of the known bat songsters and their tunes.For more, see the News Feature in this week’s issue of Science.