Why do birds sing?
This may not be the first thought that pops into your head, as you enjoy the beginnings of spring’s chorus of bird song. Already as we return home from work in the evening the blackbirds in our gardens are singing their wonderful fluting song, and weekend walks in the countryside are accompanied by the rising crescendo of sound that follows a skylark’s rise into a vast blue sky. Why these birds are singing is a question worth asking, as the answer explains why birds put so much effort into doing something that in turn gives us so much pleasure.
But before I continue, perhaps I should explain how birds sing. Birds do not whistle. The opening and closing of a bird’s beak, whilst it is singing, is to enable the bird to take in air, not as you might at first think, to enable the bird to sing different notes. The sound that a bird makes when singing is generated by an organ known as the syrinx, this is positioned at the end of a bird’s wind pipe where it divides in two. This explains how birds can sing two notes of differing pitches at the same time.
As anyone who is fortunate enough to have a resident wren in their garden will be able to testify, size is not an indicator of how loudly a bird can sing. Indeed it is often the case that the larger a bird, the less impressive the noises it makes can be. Birds of prey, whose often impressive size and position at the top of the food chain might lead you to think that they would have fine voices, in fact emit weedy high pitched calls. Although with their tremendous roller-coaster courtship flights, species such as the Marsh Harrier can be said to more than make up for what they lack in a singing voice with a spectacular display.
So why do birds sing? There are three main reasons. Firstly to attract a mate. Male birds by singing not only draw attention to themselves, but also offer females of their species a means of judging their suitability to be the father of their young. The bigger and better the voice, the healthier its owner, the better his genes and the more use he is likely to be in bringing up a family. An example of this is the Skylark where females have been shown to prefer males with a complex song when it comes to choosing a mate.
Song is also important as a way of letting other birds know you are there. Often in the woods where birds live, it is difficult to see your neighbours due to the dense vegetation. A visual display would not be of much use in this habitat, but by using sound, you can make your presence known to both prospective mates and to warn off rivals for your territory.
Establishing a nesting territory is the third reason that birds sing. Familiar garden birds such as the Robin, Blackbird and Song Thrush sing not only to attract a mate, but to declare the boundaries of their territory to other male members of their species. The defence of a breeding territory is vitally important, because as well as providing a safe nest site, it also needs to be big enough to supply its owner, his mate and their young with all the food that they will need.
Whilst for birds, song has an important practical function, people love bird song for its intrinsic beauty and melody. Here in Essex we are blessed with some of the finest song-birds in the world, whose calls and songs are an integral part of the local countryside. Who, for example, could imagine a walk along the edge of coastal marsh in the spring from which were missing the towering song of the Skylark and the warning call of a nesting redshank.
You do not need to go out into the wilds to listen to a chorus of bird song, just step outside the backdoor and into your garden. Here a range of species that have learned to live with man will entertain you and bring the sound of the wild right into your home.
All these bird songs and calls can be very confusing to the inexperienced ear. But now is a good time to start to learn the songs of your local birds, before the leaves open on the trees and the summer migrants arrive,
There are many different ways to do this. One is to listen to a CD, DVD, Video or audio cassette of bird songs. But the best way to learn is to go out and listen to the birds in your neighbourhood, tracking down each song that you hear to its source and identifying the bird making it. Although birds will sing during the day, they are at their noisiest early in the morning and again in the evening and these are the best times to listen.
Robin: Andy Hay (RSPB). Skylark: Chris Gomersall (RSPB). Female Blackbird: Chris Mills (RSPB)
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