Grist to the Mill

04 April, 2004


Why do birds sing?
To advertise themselves to potential mates and also to deter rivals from their territory, thereby avoiding the need for physical fights. The dawn chorus reaches a peak in May and June when migrant birds arrive.

The sky starts to get lighter an hour before sunrise and the chorus begins when it is still dark – continuing for up to two hours.

Humidity enhances sound transmission, and rain may not depress the chorus. At very early hours the air is still, which allows sound to carry further.

It is assumed that unmated birds sing the most, but newly-mated birds behave like unmated males in the morning. They sing very loudly until the female appears. As soon as the hen is around, the cock suddenly stops singing.

Early starters: The Songthrush, Robin and Blackbird are thought to rise earlier because they have large eyes. Common to all three is the earthworm. Earthworms live in burrows under the ground and feed on dead leaves and animals, which they bring down to their burrows from the surface. They dislike heat and sun, sometimes coming to the surface only at night. They leave their burrows when it rains as it is easier to move over wet grass. It is advantageous for birds that feed on earthworms to rise while the worms are still on the ground rather than beneath it. The Skylark, usually the first bird to sing, is a ground-feeding bird that cannot dig worms out of the ground. It therefore rises when earthworms are most accessible. The times that birds rise also depends on light. These birds have evolved to rise early (in the dark) and must have large eyes to forage by.
Late starters: Warblers, Chiffchaffs, Wrens, etc have smaller eyes; they feed on insects rather than earthworms. However, because most insects are not active at dawn (because of cooler temperatures), there is little incentive for these birds to rise early, which is probably why thy do not join in the chorus until later.

Type of song
By whispering the syllables/phrases of a bird, it is possible to mimic the song. The song of the yellowhammer sounds like ‘A little bit of bread and NO CHEESE’; the woodpigeon’s song sounds like ‘Take TWO cows taffy’ [surely, ‘twit twoo’?!]

Thanks to Michael Demidecki

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