It's the unmistakeable sound that spring is well and truly underway: the woodlands, gardens and parks throughout Britain filled with the songs of birds. Birds songs are used to advertise their location, claim territory or communicate sexual intentions, making these 'songs' distinct from contact and alarm calls. Birds produce sounds from an organ known as the syrinx, situated where the windpipe splits off to the lungs. The 'true songbirds' (Oscines, Passeriformes) have the most complex musculature of the syrinx and can produce sounds from both sides simultaneously.

Birds rarely sing throughout the year and some may only sing for only a short period annually. Singing, a crucial part of the breeding season for birds, is controlled by hormone levels. Generally it is the male that produce songs, however some species females do also and may even duet in pairs. Learning can play an important role in the production of song. Whilst some species can produce their song without ever hearing another of the same species, others must hear an older bird sing in their first year (the critical imprinting period) in order to produce the full song. Vocal learning is thought to have evolved in three separate lineages of birds; oscines (true songbirds), hummingbirds and parrots.

Bird song can be an incredibly useful tool for monitoring birds. Firstly in terms of identification; some species such as warblers can be extremely difficult to distinguish between visually, especially at a distance. Bird song is often the only practical way to assess woodland bird populations as accurate visual counts are challenging, if not impossible. During repeated visits to a site during the breeding season, singing birds are often recorded onto a map. This allows breeding territories to be mapped and the number of pairs in an area to be estimated.

Identifying birds by their song can be a daunting task to a beginner and in truth it can take years to confidently recognise a majority of our native birds. But it can be immensely rewarding to be able to walk through the countryside and recognise even a few species. Singing activity tends to increase in April as the breeding seasons get underway. During a day the greatest amount of bird song can be heard from dawn to around mid-morning. However there can be such a cacophony of songs in early morning it can be difficult to pick out one species as a beginner and you may wish to start later in the day.

There are a number of great books that give guidance and are typically supplied with recordings to listen to for reference. Multimedia guides have the additional benefits of sound clips, video, photographs and drawings to aid identification. The RememBird is a great little device that attaches to binoculars to allow you to record bird songs without taking your eye off the bird. It can also be loaded with reference calls to act as a song guide. Many RSPB and bird watching groups offer guided walks to get you started on learning birds in your area.