There are an almost infinite number of animal sounds in the animal kingdom and an almost infinite number of musical instruments in Bill's house. Using his fine collection he shows us that almost every instrument has its natural equivalent. Drumming, blowing, plucking has all been done before and some might say the animals are the real professionals. Bill and John are in Norfolk where Bill sets his latest challenge. John has to film the sky dancing courtship behaviour of the male marsh harrier in just one day. John's only ever managed to film it once before and all seems to be conspiring against him. Chris is in the quietest place he has ever been too, a peat bog in deepest darkest Scotland. A nightmare you would have thought for wildlife sound recordist but Chris, armed with his collection of high tech gadgets, adopts his specialised working position of lying down and shows Bill that even here there's plenty to listen to. Seabirds and humans have a complicated history. Bill travels to a seabird colony to pick it apart. Whether they were the souls of children lost at sea, a tasty snack or a fashionable hair product, seabirds have played an important part to seaside communities. But could the attributes that made them so vulnerable help succour their future? Bill investigates. And finally we join Bill in his back garden for his world famous meal worm challenge. The rules are simple; you just have to see how many worms you can get in your beak in the shortest time.