Twitchers, birders, ornithologists and garden-tickers: there are many species of birdwatcher, and they're all catered for by this unique book. From the serious (why vultures are dying out in Asia) to the bizarre (the parrot that can read minds); the informative (why waxwings have waxy wings) to the completely ridiculous (the avian footballing XI, starring Bobby Moorhen and Jimmy Grebes), 'The Birdwatcher's Companion' takes the reader through a veritable aviary of notes, quotes, facts and stats.   But 'The Birdwatcher's Companion' doesn't just contain fascinating snippets of information, it also offers extracts from the finest writing about birds over the centuries. Gilbert White shares space with Chaucer, while Flora Thompson nestles up to DH Lawrence. And like all the other books in the 'Companion' series, there's a magnificent piece of statistical trivia to match each page number.   The market for this book is huge: Britons are birdwatching like never before. The RSPB alone has over one million members, while sales of garden bird food topped the £100 million mark last year. Of the three leading newsstand wildlife magazines, two are about birds, and the ratings for Bill Oddie's recent garden wildlife show, with its particular focus on birds, topped those of many soap operas.