|Image by Malene Thyssen|
One of my favourite things about April is that the birds are in full song. Many people don't realise this, but with a few exceptions such as the robin, birds don't sing all year round. They may call to one another, either for contact or to raise an alarm, but they only actually sing during the breeding season, to attract a mate and defend a territory while they raise chicks.
Once the chicks have flown - and some species may rear several broods - many birds go into moult, shedding old and damaged feathers and replacing them with new ones. It's a vulnerable time when their ability to fly may be impaired, and most birds hide away; they certainly don't sing, as that would attract attention. August, therefore, is known as 'the silent month', but even after the moult is over and birds are seen again in parks and gardens, most will be rarely heard from until the following spring.
But now is the season of birdsong, and of all the city birds, the blackbird is the one whose song most defines the urban streets. At dusk every evening they take up position all over the city: usually somewhere high, like a roof tile or a lamp post, so that their song will carry. They'll pour out a carillon of notes, cock their head to the side and listen for their rivals' reply; then answer it with a phrase even more intricate, more complicated, than his.
Blackbirds pick up sounds almost as easily as starlings, and you'll often hear the notes of a car alarm or mobile phone among their repertoire. They do it, quite simply, to show off: it's a way of saying, "Look how far I've travelled, look how much I've seen and heard: consider how fit and strong I must be to have done so."
Male blackbirds establish a territory in their first breeding season and will try to hold it for the rest of their lives; so the bird you see in your back garden today could well be the same one you saw last year, and even the year before that. It's hard to tell by looking, but if you listen out it's fairly easy to tell one from another by their songs. We can recognise one who sings in our damson tree by the fluting trill he finishes many of his phrases with, making his song instantly recogniseable from the bird who sings a few doors down.
For more on the blackbird and its beautiful song there's a short film here (warning: contains Titchmarsh).