Predators, such as hawks and foxes, have keen eyesight and sharp beaks and teeth to help them catch their prey. Prey, such as mice and rabbits, have large ears to hear danger and can move quickly to escape their enemies. Animal populations are closely integrated with each other and the surrounding environment. A change to one population causes changes to all others. Readers discover how repercussions can affect nature, including humans, and are encouraged to consider their own actions with an eye toward the effect on the environment.