Britain's population of nightingales, the world's most celebrated songbirds, has crashed in numbers by more than 90%, new research has shown. Although there have been concerns for some time that nightingales are declining, the scale of the fall has come as a shock to researchers at the British Trust for Ornithology (BTO), who uncovered the trend. The drop is the biggest fall in numbers since records began of any bird still breeding in the UK, apart from the tree sparrow, whose numbers have been decimated by intensive farming and which has dropped by 93%. "For every 10 nightingales which were singing in Britain when I was born 40 years ago, only one is doing so now," said the BTO's Dr Chris Hewson. "The rest of them have vanished. That's the scale of what we're talking about. Pretty sobering, isn't it?" Famous for its powerful singing in the dark, and celebrated by poets since classical antiquity, the nightingale is the most versified bird in the world. In Britain it has been lauded by poets from Chaucer onwards, most notably John Keats in his much-quoted Ode to a Nightingale, inspired by a bird he heard in a garden in Hampstead, North London, in 1817. Once familiar to everyone in southern England during the six weeks when it sings from mid-April to June, the bird has now disappeared from a huge number of locations in the countryside and as a consequence organised 'nightingale walks' are attracting more and more participants.