Wolves of Yellowstone. In 1995 the grey wolf was reintroduced to Yellowstone National Park, prior to that elk, deer, and bison over populated the park causing rivers to stop, cascade waterfalls and the demographic to completely change and die off. After the reintroduction wolves thrived, Yellowstone once again was home to beavers who build dams creating the cascade waterfalls to flow, creating rivers to flow and brought back the beauty of the Park. Today in Montana wolves are not protected, hund