What is a bird? And how is it different from a mammal or a reptile? Some birds are huge and some are tiny. Some birds are fantastically colorful and some are plain. But what do all birds share? Early nonfiction expert Lizzy Rockwell explains that birds have beaks, wings, and feathers, and hatch from eggs. Other animals might have some of these features in common, but only a bird has them all. Only a bird is a bird! A clear text and beautiful illustrations cover dozens of different birds and their shared characteristics, as well as the unique qualities of unusual birds, such as penguins and peacocks. A great companion to Rockwell's A Mammal is an Animal.