The varied vocal utterrances of a wide diversity of birds, particularly of the large suborder Oscines (order Passeriformes) also known as 'songbirds'. In a more defined sense it is a series of notes, generally of more than one type, uttered in succession and forming a recognizable sequence or pattern in time with a characteristic complexity of rhythm and modulation, thus being distinct from a general succession of call-notes (see 'call(-note)'). This pattern may be repeated exactly and is consequently recognizable at the group, but also the individual level. Each particular song can be visualised and analysed by means of a sonagram. Song is primarily under the control of sex hormones and concerned with the reproductive cycle, while call-notes function as a means to co-ordinate actions with other member of the species in normal (non-sexual) situations. Song is of great importance in the establishment and defence of territory (serving as a substitute for combat) and probably also in maintaining the pair-bond and the mutual adjustment of the sexual cycle of a pair, thus being a form of sexual display. Another difference is that call-notes and their response are always genetically determined (inborn), while song can also be learned.

Alternative form for song : songs.