In this Sept. 13, 2019, photo, provided by the National Park Service, bison enter a corral on the North Rim of Grand Canyon National Park, Ariz. Over 30 bison roaming Grand Canyon National Park's northern reaches are joining a herd in Oklahoma. Hundreds of the massive animals have made their home at the Grand Canyon in recent years, but park officials say they're spoiling water sources and harming the landscape. (Bryan Maul/National Park Service via AP)