Dawn Chorus Special – Bird Vocalisation
Spring is the time of year of the dawn chorus, that time of year when our garden birds make an abundance of noise early in the morning to find a mate, to breed and produce young.
But, what of this noise, what does it mean, what variations exist and, controversially, are there universal patterns to be found that may suggest a limited yet meaningful expression of language? These orchestrated sounds were hidden from human understanding for millennia, but now we have a deeper understanding of their purpose. Charles Darwin wrote in The Descent of Man that the sounds uttered by birds offer in several aspects the nearest analogy to language. Further to this, there is strong evidence that birds may hold an important key to the great mystery of how human language evolved.
In its most fundamental form, bird vocalisation consists of two core elements: bird song and bird calls. The difference is vast and each display consists of a completely different range of emotions and feelings, based on, of course, personal requirement, situation and need.
Listen to the long, rhythmic and complex repeated patterns of bird vocalisation and you will hear bird song. This beautiful sound of nature can be expressed in a number of different forms, from high shrills to liquid, soothing melodic fluting. It is primarily used as a tool for attraction, mating and courtship and provides a clear indication of male ‘fitness’; unhealthy males, particularly those with parasitic infections affecting the syrinx, often cannot express correctly, which affects their ability to mate and, ultimately, breed young. Bird song is, therefore, a basic requirement of reproduction in birds. Some birds have a great diversity of songs, with one in particular, the brown thrasher (T. rufum), being known to have 3,000 in total.
Listen for shorter, stuttering sounds that stop and start, and you will hear bird calls. These non-melodic sounds communicate more directly various emotions related to aggression, agitation and alarm. Bird calls are also commonly used as a tool for coordinating migratory flocks; sometimes you may hear these short notes drip down from the sky, and what you hear is the collective communication of a flock of birds in flight. These small yet important snippets of information are basic, but do not suggest a similar recursive grammar system as that found in human language.
Avian vocalisation is produced in a fundamentally different way to human sound. Birds use a bony structure called a syrinx, which is located at the bottom of the trachea or windpipe – this is in contrast the human larynx, which is located near the top. As the trachea is contracted and expanded, it is possible for birds to product two notes simultaneously, making for interesting songs and calls.
Next time you are in your garden, perhaps enjoying the morning air while listening to the symphony of birds, take time to listen to all the different calls and songs; take the time to enjoy their meaning and listen to the sound of nature in action. It’s a beautiful spectacle, one we should all cherish and protect.
*International Dawn Chorus Day is on the 1st May. Join in and listen to your garden birds.