The Dawn Chorus in Britain: Why It Happens and How to Listen

Set the alarm for half three and you will wonder why you bothered. Then a robin starts somewhere in the dark, a song thrush takes over, and inside twenty minutes a hedgerow that looked completely empty is louder than the road. Britain's dawn chorus is the biggest free wildlife event of the year, and it happens in churchyards, allotments, back gardens and city parks as readily as it does on a nature reserve.

What follows is the why, the running order, and a workable way to hear it properly.

Why the chorus happens before sunrise

Two things make the hour before sunrise worth singing in. The first is that there is nothing better to do. Light levels are far too low for most small birds to find food — a blackbird cannot flip leaf litter at four in the morning any more than you can read a newspaper by moonlight — so the time is free.

The second is acoustics. Air near the ground is cool and still before dawn, there is little wind to distort sound, and there is almost no human noise. A song delivered at 4am carries further, and more cleanly, than the same song at noon. For a male advertising a territory and trying to attract a mate, that is a good deal.

Timing matters for another reason. Song is most intense when territories are being contested and females are making choices, which for most British species means spring. Residents such as robins and blackbirds hold territory all winter and start singing early; by the time the warblers arrive from Africa in late April, the airwaves are already crowded.

How the morning unfolds

A dawn chorus has a shape. It builds in a wave, peaks in the half hour or so around sunrise, then thins out quickly as birds turn to feeding. In southern England in mid-May, when sunrise falls at about five o'clock BST, the first songs can begin a little after three and the main event is largely over by six. Further north and west, sunrise is later and the whole thing shifts with it.

The gap between first song and sunrise widens as the season progresses: barely any singing in the depths of winter, then a start of an hour or more before sunrise by late spring. Weather changes the picture too. A calm, mild morning produces the fullest chorus; wind, heavy rain and cold shut it down. Listen on a still morning after a warm night and you will hear twice as much.

The peak season runs from roughly mid-April to early June, usually strongest in the first half of May. July is thin and brief. There is a modest revival in late summer and autumn, when robins sing again, and in towns you can hear robins at two in the morning under street lights, apparently convinced that dawn has come early.

Who sings in what order

The classic running order runs roughly like this. Habitat, weather and light all shift it, so treat it as a guide rather than a timetable.

1. Robin. Usually first, sometimes a full 90 minutes before sunrise: a thin, wistful warble with clear pauses between phrases.
2. Song thrush. Loud, confident phrases, each one repeated two or three times before moving on. That repetition is the giveaway.
3. Blackbird. Low, mellow and flute-like, with unhurried pauses. Improvised rather than repeated.
4. Mistle thrush, wren and dunnock. The wren's song is astonishingly loud for its size — a fast, rattling burst with a trill near the end.
5. Blackcap, chiffchaff, willow warbler and garden warbler. The migrants join as the light improves, adding a layer of thin, hurried songs.
6. Great tit, blue tit and coal tit. The great tit's two-note "see-saw" and ringing "teacher, teacher" make it sound as though the chorus is being conducted by a small, bossy bird.
7. Chaffinch, greenfinch and goldfinch, then woodpigeon and collared dove. The woodpigeon's five-note coo is a useful marker that the performance is winding up.

Why some birds start so much earlier

Eyes are part of it. Species with large eyes relative to their body size — robins and blackbirds are the obvious examples — can see well enough in very low light to feed. That means they can afford to sing first. Small-eyed species that struggle in the half-light must wait until there is enough light to eat, and sing afterwards.

Choosing a place to listen

You do not need a famous reserve. What you need is a boundary. The best choruses come from the edge of woodland, a long mature hedgerow, a churchyard with old trees, a canal towpath or the scrubby end of a park. Open fields are quiet; a thick, varied strip of vegetation with somewhere to perch is a stage.

• Pick a spot you can reach in the dark without a map.
• Face a hedge or wood edge rather than standing in the open; sound travels along vegetation lines.
• Arrive 20 to 30 minutes before the first song is due, and then stay still.
• Take a red torch or a dimmed screen. A white light waved about spoils it for you and disturbs the birds.

Listening well

Learn three songs before you go, not thirty. Robin, blackbird and song thrush will carry you through the first half hour, and great tit will tell you where you are. Listening to recordings the evening before is far more effective than trying to identify everything in the moment.

In the field, pick one voice and follow it until it stops rather than swinging your attention around. Cup your hands behind your ears to gather sound. Recording on your phone lets you check a mystery later, and half the time it turns out to be a blackcap

Photo: Nothing Ahead / Pexels