"What has that Thrush got to Sing About?" Asked Mr. Hardy

That dolphin who spotted the two stranded whales, and led them to safety, was the best item of news we have had for many weary weeks. There are cheerful mysteries in creation, as well as savage ones. When I was five and first went on the local train to school, I noticed the driver always shut off steam when we stopped at a little place called Cobridge, and a great silence descended. After a pause of three seconds, all the birds which lived near the umbrageous platform began to sing. I assumed they loved the engine and were welcoming it. It was just like what happened to Edward Thomas when his train stopped at Adlestrop, and a blackbird sang until, as his delightful poem relates, it was joined by 'all the birds of Oxfordshire and Gloucestershire'.

Song is the high road into the mind of a bird. Thanks to the recording and analysis of birdsong, we know much more about birds than any other creatures of their size. Yet we know very little really: not much more than Plato, over two millennia ago, who thought that birds sang because they were happy, or Pliny, who believed magpies died of intellectual despair if they failed to master a sound they wanted to copy. The French composer Olivier Messiaen spent much of his life studying and writing down birdsong, including the Australian lyrebird, finest of all songsters. Yet the music he wrote recreating birds singing does not seem, to my ears, to work, any more than the passage in Beethoven's Pastoral Symphony, which he later admitted, grinding his teeth, was 'a joke'.

It is male birds, chiefly, who sing, and the primary purposes of birdsong are to defend territory and attract mates. Yet there are many other reasons why birds sing, and we can only guess at them. Between the wars, a clever lady, Mrs Nice, in Columbus, Ohio, spent a decade ringing and studying the hundreds of birds residing in the 40-acre lot behind her house. She gave them all code names, and eventually published her findings in a two-volume, 500-page book. Her favourite was M-4, a singing sparrow. She observed him closely from 1928 to 1935, during which he had 11 mates, was widowed seven times, raised 13 chicks and built 17 nests. Eventually, being old, he found it hard to get a mate, and had to settle for 'an old-maidish creature' who tyrannised him. Mrs Nice called her Xantippe, after Socrates' horrid wife. She was unfaithful, idle, refused to help build the nest, laid only two eggs, which she neglected and were quickly smashed by wrens, and then deserted him. Five days later, he suddenly began singing energetically at 4 a.m., singing his special song three times to the minute, 200 times an hour, without ceasing, until sunset. Mrs Nice had never heard anything like it. What was the purpose of this extraordinary recital? A desperate attempt to get Xantippe back? Regret? Remorse? Thanksgiving? Rejoicing by an old card who had discovered the hard way that celibacy is better than woe? Next day he resumed his normal singing but soon disappeared and never returned. Dead presumably.

I learned about M-4 and Xantippe by reading an excellent book, Why Birds Sing, by David Rothenberg, which gives the results of many similar studies. I strongly recommend it. Most people would say that the nightingale is the best singer. John Clare said that it made him a poet. Shakespeare mentions it many times, treating it as the standard of lyric excellence. All the same, why does Antony call Cleopatra 'My nightingale'? The Serpent of old Nile was not a songstress. There are countless recordings of the bird singing, and many written snatches, both in the funny notation ornithologists use and in normal musical script. They don't unlock the secret of the nightingale's charm, and no musician has succeeded in imitating it successfully, just as no painter has contrived to produce a convincing rainbow on canvas or paper.

Yet birdsong is clearly a performance, among other things. Birds that have their own song played back to them, or songs by other birds of their species, or similar sounds, nearly always react, and in a variety of ways, and often their motive seems to be a desire to improve their own performance. In Surrey, during the 1920s, the cellist Beatrice Harrison used to play in the fields, and persuaded nightingales to join in. She was so excited by the result that she got Sir John Reith to send a BBC recording team. Despite the primitive equipment then available, they made a record, and when it was broadcast it attracted 50,000 letters from delighted listeners. There is something exquisite in the idea of a bird volunteering to join a cellist in making music which, like dolphins saving the lives of whales, is an adventure across the strict taxonomy of nature which is somehow magical, yet true.

The greatest performers are of course the lyrebirds. There are two kinds: Albert's and Superb. They are no bigger than grouse but their brilliant tails, in the form of a lyre, are enormous. In the mating season they put on a song-and-dance show unique in nature, creating a stage for it. Albert's lyrebird selects four or five natural places in the clearing under the trees where it lives, and uses them alternately. But the Superb actually builds for itself a performance mound, and on this artificial stage it struts and gyrates, pirouettes and prances in a visual explosion of pride and self-love to make a peacock seem shy by comparison, and simultaneously sings a tremendous aria, imitating all the birds of the neighbourhood, and other sounds too, and repeating its characteristic notes and its signature tune. In the 1930s, in New South Wales, a farmer who played the flute kept a Superb as a pet, and got it to imitate snatches of 'The Keel Row' and 'Mosquito Dance', as played by the flute, before releasing it into the wilderness. Thirty years later, in the nearby national park, Superbs were found who incorporated fluting snatches of these songs in their repertoire. So some birds not only learn music from humans but pass it on to their progeny.

Professional research into birdsong discourages anthropomorphism in some ways, but in others confirms it. In that famous passage in Milton's Paradise Lost beginning, 'Now came still evening on', he was quite right to refer to the nightingale's 'amorous descant', though wrong to refer to the bird as 'her'. And it is arguable that Keats was also right to describe the nightingale's song as 'divine melodious truth'. There is something essentially truthful about birdsong, and the more truthful it is, as Keats always argued, the more beautiful, indeed divine. But what of Hardy's wonderful poem 'The Darkling Thrush', perhaps the best thing he ever wrote? Why should this ageing, ill-favoured bird, nearing its demise perhaps, choose one of the coldest days of the year, when every sensible creature, human or avian, concentrates on keeping warm, to pour out its heart in glorious song? Hardy, the old pessimist, for once drew a message of hope from the incident. It strikes me now that what Hardy observed was a singularity, though a truthful one not unlike the outburst of song Mrs Nice heard from M-4 when he reacted to the disappearance of his difficult mate Xantippe. It would be a miserable world where no birds sing.