This is important part in the ecological system. By enhancing the strength into the herds. Without animals like the wolf to eliminate the weak, old , sick and injured, the herd of deer would swelter. They would become so numerous that they would starve to death. The wolf helps keep them healthy by insuring the breeding of the strong.
Wolves also help feed other animals.
When a wolf kills and eats, he sometimes can't eat it all. This leftover feeds animals such as the buzzard, the possum, fox, coyotes and eagles. They help keep the forest clean by removing the sick before it can spread.