For some time, the House Rock bison herd wandered between the House Rock Wildlife Area and Grand Canyon National Park, returning to the Wildlife Area in the summers to calve and mate. However, currently bison have not returned to House Rock Wildlife Area since 2009 and due to ongoing bison hunts on the U.S. Forest Service land immediately adjacent to the Park, the majority stay inside the boundaries of Grand Canyon National Park year round, effecting ecological and cultural resources.