120 species of crows, jays and their allies exist in the world today. Many are exceedingly beautiful in colour, grace and form, whereas others are black and somewhat sinister in appearance. In no other group of perching birds has evolution produced such a degree of variation, from the tiny Hume's Ground-Jay of the steppe-highlands of Tibet to the huge Thick-billed Raven of the mountains of Ethiopia. Some have had a long association with people and appear in tales of mythology and superstition, while others have been regarded as agricultural pests. The great majority, however, remain...