IDCD

The Dawn Chorus Explained

First come the blackbirds. Then the robins, wrens, thrushes, finches and hedge sparrows.
This is the dawn chorus and the order in which if you're up early enough you'll tend to hear the song of each bird species.
But why do birds sing? And why is there a dawn chorus?
The two main reasons for male birds to sing during spring are to do with territory: advertising to females the fact that they have one, and warning off potential male rivals.
Some birds also sing as part of their courtship and, in long-lived birds, to re-affirm a previously successful partnership.
Distinctive alarm or warning calls are also given when danger threatens the pee-peep of a blackbird, for example, indicates that a predator is about, and is very different from the multi-note melody of its normal song.
It's been suggested that the dawn chorus is also a way for birds to keep track of numbers, and to identify whether individuals have arrived or have disappeared from the population during the previous day.
The birds' chorus actually begins well before dawn since the sky begins to brighten well before the sun actually appears, and it lasts for two or three hours. Early morning is the most effective time to sing since cold damp air allows a sharper sound that travels further maybe twenty times further than at mid-day.
One of the reasons for blackbirds, thrushes and robins being active first may be that these are birds that favour eating worms. Earthworms are highly nutritious 70 per cent protein and first thing in the morning they are found on top of the damp ground rather than underneath it. The early bird does indeed get the worm.
The later arrivals to the choral scene either eat insects, which become active when the sun warms things up, or seeds, which the birds can look for at any time.
Feeding habits, then, go a long way to explain the sequence of singers in the dawn chorus.
We generally think of bird song in terms of a sequence of notes that are attractive to our ears but we mustn't forget that the harsh rattle of a magpie or caw of a crow serves the same communication goals as the melody of a song thrush. Even so we do find some simple songs attractive the cuckoo's two-note call, for instance, the cooing sounds of a wood pigeon or collared dove, and the hootings of a pair of tawny owls (the kee-wick of the female and the male's whoo-whoo response).
Dr Peter Jarvis Trustee, The Wildlife Trust for Birmingham and the Black Country
Thanks to the Express and Star Newspaper for permission to republish this article