Imagine a jazz musician, improvising on a theme. Then imagine that he is able to play half a dozen instruments - not one after another, but almost simultaneously, switching effortlessly between instruments and musical styles with hardly a pause for breath.If you can countenance that, you are halfway towards appreciating the extraordinary song of the nightingale . . . Wherever we are, there are birds. And wherever there are birds, there is birdsong. It's always a pleasure (and a relief) to hear sounds which prove the world's still spinning: whether it's the sighing of migrating redwings on a damp October night, the twitter of swallows fresh in from South Africa in April or the call of the cuckoo in May.Based on the scripts of BBC Radio 4's beloved year-long series, and distilling two lifetimes' knowledge, insight and enthusiasm into these pages, Brett Westwood and Stephen Moss take you month by month through the year, and the changing lives of our favourite birds.From peregrines swapping sea-cliffs for skyscrapers to swifts spending almost their entire lives on the wing; from charms of goldfinches to murmurations of starlings; from ptarmigans thriving in the Highland snow to the bright green parakeets thronging London's parks; this book is packed full of extraordinary insights and memorable facts.Tweet of the Day is a book for everyone who loves Britain's birds. (Illustrations © Carry Akroyd)