It’s International Dawn Chorus Day and I’m on my way to Wormwood Scrubs in west London — not to serve time at her majesty’s pleasure but to meet with a group of birdsong enthusiasts.

“He’s been looking for a mate now for three weeks,” David, our birdsong expert, seems genuinely concerned as we listen in silent rapture to Wormwood Scrub’s most eligible willow-warbler showing off his vocal skills: “he’s flown all the way from West Africa but is still single.” Being able to lay down a good tune is the avian equivalent of a man with lots of money, a sense of humour and a great figure. But there’s a lot of competition at this time of year and zero fidelity. The window of opportunity is brief so you either sing your heart out or find yourself left on the branch.

David Lindo, aka the Urban Birder, is endearingly passionate about his subject: “Hearing all these wonderful songs really grounds me for the day”. And with that he suddenly cocks a finger to the sky. “Hear that?” he whispers, “A black-cap. Lifts the heart, doesn’t it?” The black-cap’s intricate trills and chirrupy crescendos fill the crisp morning air.

As the first rays of sun bleed into the early morning sky the birdsong grows ever more cacophonous. David notices a tiny out-of-season robin. “Although I love birds,” he says, “I’d hate to be one. It’s a constant battle for survival and it’s not just about finding a mate. Male birds are very territorial; they use song to ward off competitors.”

Being able to lay down a good tune is the avian equivalent of a man with lots of money

It appears birdsong isn’t quite the exuberant celebration of life I’d imagined, more a desperate plea for copulation or a stern warning to intruders. Odd then that this battle cry should be so appealing to human ears and I wonder if there is some deeper, hidden meaning there. Ornithologist William H Thorpe wrote that: “The songs of birds can be regarded as a first step towards true artistic creation and expression.” There is even evidence to suggest that birds enjoy singing because of the complex musical phrasing; if song were merely functional then short, repeated sounds would presumably be adequate.

Further evidence suggests that birds employ musical devices such as accelerando, ritardando, crescendo and diminuendo indicating they have a sense of musicality and it seems that long after certain birds such as blackbirds and willow-warblers have found a mate and established a territory, the males continue to develop their songs musically, suggesting they find pleasure in the creative process.

Daines Barrington, the dedicated naturalist and author of The Language of Birds awarded marks out of twenty for the different aspects of birdsong. He gave the skylark nineteen points for “sprightly notes”, eighteen points for “execution” and another eighteen points for “compass”. The woodlark, a close relation of the skylark, received eighteen out of twenty for “mellowness of tone”. The blackbird is known as the Beethoven of the bird world because of its mellow flute-like song while the song-thrush has over two hundred tunes in its repertoire.

Top of the ornithological pops has to be the rich and spirited voice of the nightingale. Roman philosopher Pliny the Elder wrote, “There is not a pipe or instrument in all the world that can afford more musick than this pretty bird doth out of that little throat.” Tennyson believed that, “The music of the moon sleeps in the plain eggs of the nightingale.”

Much of the pleasure of birdsong lies in its mystery. We can never truly understand what all those tuneful tweets and tremulous twitterings mean — but at this time of year there really is no sound lovelier.