The author and zoologist Professor Valentin Häcker (1864-1927) describes in this volume the song of birds and its anatomical and biological foundations. Birdsong is a complex behavioral biological achievement. Birds sing, among other reasons, to attract mates and to mark their territory. Females receive cues about the performance and health status of a suitor through this. The songs of many songbirds are structured in stanzas and are often very varied. Unlike other bird species, the song of songbirds is not innate but must be learned. However, there is a predisposition for the species-specific song, so even the few instances or a single perception of a singing conspecific can lead to successful learning. Among native birds, for example, the nightingale has a very complex song.