Ages 6 to 12 years. All birds are warm-blooded, have wings, a beak, feathers, and a backbone. There are, however, over 9,000 species of birds in the world so all birds are not the same. This book describes in a clear, simple way: a bird's body; facts about beaks, feet, and feathers; how birds fly and why some can't; where different birds live and what they eat; eggs and chicks; bird songs.