This story simply rests upon the winter migration of a family of whistling swans from the Arctic to the Sacramento Valley in California. There is little fictionalization. The Old Cob and his Pen and their cygnets are, of course, the authors' creations, but the resemblance to real swans is certainly not coincidental. These birds have been widely observed along their route, and this book contains a great deal of information about their habits, characteristics, and flight patterns, as well as indicating the wildlife refuges that shelter them and the methods by which they are traced. Not really a story, the book is a reasonable, well-written natural history. For those with an interest in birds, the flight of the swans is in itself a lift to the imagination.