Birds produce song with the syrinx — a dual vocal organ at the bronchial junction, unique to birds, allowing independent control of each bronchus. This enables extraordinary complexity: nightingales produce 200+ distinct song types. Unlike mammals, songbirds are vocal learners: juveniles pass through a critical period, memorizing a "tutor template" from adults, then practicing (subsong → plastic song → crystallized song) via auditory-motor feedback involving specialized brain nuclei (HVC→RA→nXIIts pathway). Regional dialects emerge from cultural transmission. The dawn chorus occurs because cold dawn air carries sound better (+20% propagation) and females are most fertile at sunrise — honest advertising of territory quality.