The reintroduction of wolves to Yellowstone National Park had a positive impact on the beaver population. With the presence of wolves, elk populations decreased as they were a primary prey of the wolves. This decrease in elk populations allowed willow and aspen trees to grow back along stream banks, providing food and habitat for beavers. The beavers then built more dams, which further improved the habitat for other species. As a result, the beaver population in Yellowstone National Park increased and flourished after the reintroduction of wolves.
