Our natural world is increasingly fragile. Now more than ever, it's important to learn about keystone species--those species whose removal can topple entire ecosystems. Beavers create and maintain their own habitat. They alter the landscape to suit themselves, thereby providing homes for a myriad of other plants and animals. This book introduces kids to the concept of keystone species and describes beavers' important role in their habitat. Simple text, full color photographs, and fascinating fact boxes help kids understand beavers, their wetland habitat, and all the other creatures that share their ecosystem.