A herd of bighorn sheep browse along Zion National Park's east entrance road. Wild sheep have thrived in the park since their reintroduction, their numbers growing to the point that park officials are now concerned that they may be exposed to domestic sheep on ranches on the Utah park's periphery. To reduce the chances of domestic sheep passing diseases to wild sheep, the National Park Service has authorized Utah wildlife to relocate some of the park's bighorns to areas where game herds are struggling. Photo by Brian Maffly, Nov. 5, 2017