I emerge from the gloom of the woods to a stain of sunrise above the far trees. The meadow is encircled by a bower of song. Thrush species dominate: a blackbird’s languidly phrased minor notes; rival song thrushes brandishing what the poet Katharine Towers aptly described as “tried-and-tested triplets”; and distantly, the urgent strains of a mistle thrush. Against this musical canvas, a nearby robin skirls plaintively. From the foliage behind him, my ear catches a whispering crescendo – its squeaky tone and rolling delivery make the goldcrest a cinch.
The woods are a battlefield, and not just between opposing males of the same species. The dawn chorus sounds like an orchestra, but is really a sonic ecosystem where the competition to be heard has driven every species into its own special acoustic niche. So each – here’s the shivering flourish of a blackcap – can be sifted from layers of sound.
Spectrograms, which convert sound into a visual trace to be dissected and measured, show that the songs of close relatives – like thrushes – are structurally very similar; distinct voices evolved from changes in pitch and tempo. This is convenient for me. Walking at first light in this popular area has shifted my bird-watching to dedicated bird-listening.
Beyond the trees, there’s a growing hum from the A55, the city’s outer ring road; and as if on cue, a great tit saws his repeated chimes into the chorus. The great tit was the first species to reveal how, confronted by the urban racket, birds can tweak the pitch of their songs to a higher register. This means, like the wheedle of a goldcrest that’s audible through robin song, they are a rung above the background din. They also sing more loudly. And they may adjust the timing of their singing by avoiding the worst of the morning rush hour, and by singing more briefly during its rumble.
But if this great tit fledged last year, he learned how to sing in another world. When he was a nestling listening to his elders and, over the winter, while he was practising his juvenile verses, this was a quieter city. Now it’s resuming its former noisy ways. My fingers are crossed that his song is fit for it.