Now the interesting facts about birds we have always with us. We can find them out for ourselves, which is a very pleasant thing to do, or we can take the word of others, of which there is no lack. But it is the quaint fancies about birds which are in danger of being lost. The long-time fancies which the world's children in all lands have been taught are quite as important as the every-day facts. They show what the little feathered brothers have been to the children of men; how we have come to like some and to dislike others as we do; why the poets have called them by certain nicknames which we ought to know; and why a great many strange things are so, in the minds of childlike people. (Summary from the book's introduction)