As well as delving into all aspects of the bird's ecology, this book provides charts and illustrations to enable readers to age owlets and unravel the complex sequence of moult in adult birds. It also includes maps showing the bird's distribution and abundance for every county in Britain and compares these with the populations reported fifty years earlier. Maps are also used to illustrate the world-wide distribution of the 37 races of the Barn Owl and the sizes of the populations in every European country.