The role of bird sounds in identification has long been underestimated and is often misunderstood. Bird identification has typically revolved around plumage colours, structural features and behaviour: visible features over visualisations. It is not unusual for entire publications to contain no reference to calls or songs at all, and written descriptions in field guides tend to be of rather limited value. Consequently, the ways many identify and describe bird sounds is haphazard. It is notoriously difficult to describe to someone else why a bird was what you heard it to be.

Bird sounds and bird behaviour are inextricably linked. Many bird songs may be beautiful to listen to, but birds are not singing for our (or their) pleasure. Different species make a variety of calls, for example alarm calls, flight calls, territorial songs and so on, and can also use the same vocalisations for more than one purpose or strategy.

There can often be occasions when it is difficult to know where to draw the line between a ‘song’ and a ‘call’, and it is best not to be too rigid in making those distinctions. Songs are assumed to be complex and can be melodic, and are associated with mating, territory and displaying. Calls are assumed to be simpler and relate to alarm, flight or, in the case of chicks, begging for food. However, this is a drastic over-simplification. Many birds ‘sing’ although we do not associate them with pleasing harmonies (think of ducks, owls, divers, for example), but the purpose behind these sounds is the same as that of a Nightingale’s tuneful song.