Yellowstone National Park biologists noticed that the food chain was not complete and there were no predators to control the population. Candian biologists with the help of US Fish and Wildlife Service managed to capture 14 wolves and released them in Yellowstone National Park. They did not predict happened next, by introducing the wolves the land around them began reshaping itself. As if mother nature was healing herself, the trees grew bigger, new breeds of animals came back into the land and the lakes reshaped themselves to supply more water.
Wolves Re-Introduced To Yellowstone National Park, The Outcome Is Amazing
How Wolves Change Rivers