Information about Wildlife Vocalisation

Ways of Singing

Just as we humans take different approaches to music for different contexts, so it is with the birds. Young birds crying - sorry, begging - to be fed (OK, not strictly speaking music, but performing with sound to get a reaction); juveniles babbling away learning to use their syrinxes and maybe even practising singing, heavily influenced by adults of their species; the softer half-songs of a large flock amassed like the rich murmur of a church congregation; the excited, inventive, intimately-seductive singing of a male passerine courting a female close-by; the playful variations on the call-note theme of a charm of goldfinches, using music to keep it together; the strict, formal exactness in the duet of a pair of African shrikes - we two are one. But best-known, and what is usually meant by 'bird song', is the full song of a breeding male of any species - often quite formal, usually seasonal and delivered in full voice. For most species of bird, the ability to deliver a good rendition of the species' full song gains respect among its peers for an individual. The kind of respect that is attractive to females and puts other males off making a challenge for territory. With species whose breeding behaviour is less territorial, it's often difficult to distinguish a full song, as such.

Why Do Birds Sing ?

Behaviourists believe that full male song has a dual function: to maintain a territory and to attract a mate. It has evolved as a way of dealing with sexual selection and breeding that avoids direct confrontation and the potential injuries of fighting; a lesson in civilisation. Loudness and sheer length of time spent singing become true indicators of physical fitness and as you might expect these are frequently the qualities that attract a female. But not always.

Female Attraction

For the last decade or so researchers have been been testing various hypotheses by observing the reactions to playback of a species' song. This is been particularly revealing on the qualities of male song that attract a female: sedge warbler females for instance show a preference for males that sing complex songs. Does this amount to aesthetic selection?

Soft & Intimate

The 'full song' of a male in spring, though the best-known, is not the only form of singing birds indulge in; researchers are now beginning to find that quieter singing (hence often passing unnoticed by 'observers') plays an important role in the lives of most species and is often also produced by females. Such 'subsong' can be heard at almost any time of year, but particularly in autumn and early spring. It may be a young male blackbird practising softly by itself inside a thick shrub, audible only from a few metres, or it may be the massed, soft flutey piping of several hundred golden plover gathering on an autumn estuary. And in moments of more intimate courtship many males sing at their best, but usually with voice at only about half volume and without the formal structure of full song.

Mimicry

Psychologists agree on the importance of mimicry in learning behaviour. Musicians develop their skills by copying the 'licks' of their favourite instrumentalist; and mimicry is a recurrent feature in bird song across many species. Starlings, common urban birds in the UK, are outstanding mimics; I've heard a Felton starling weave the calls and songs of a dozen or more other bird species, a car alarm and the squeels of children in the nearby schoolyard into the fast trilling and bill clicking of its song. Individual marsh warblers have been found to use the mimicry sounds of over a hundred other species including those encountered in Africa during the winter. A Belgian researcher actually tracked down the region of Africa where the warblers had picked up their copies by identifying the species being copied.

Individual Recognition

Most people know that each species of bird has its own characteristic songs and calls and with a bit of practise you can begin to recognise species by ear. You may have read about regional dialects in some species' sounds. But it's also possible to recognise an individual bird by idiosyncracies in the sound of its voice or its calls and songs; birds themselves can recognise known individuals by voice, but we usually need the help of a computer. Dr Gillian Gilbert at the RSPB has a voice print (sonagram) for each of the dozen or so male bitterns that sing in Britain.

Cultural Tradition

Birdwatchers start by looking for what different birds have in common - characteristic markings or sounds that enable us to identify the species. But in time, if you become very familiar with the song of any species, the differences strike you and you realise their individuality. Each individual shows different preferences in its behaviour: birds of different ages sing and call differently; a young bird's singing tends to be more experimental and variable than an older bird of the same species (cf human youth music). But, because a young bird achieves its vocal ability by listening to and copying the adults it hears, each is an example of the particular cultural tradition it was brought up in.