Between 1995 and 1997, 41 gray wolves were reintroduced to Yellowstone National Park. Their 70-year absence had a huge knock-on effect across the park’s ecosystem : the elk population expanded unchecked, overgrazing on willow and aspen trees, and in turn, beavers had no food or shelter, and almost disappeared from the park too. As of January 2020, there were at least 94 wolves in the park, and more than 500 in the greater area, but the program has struggled to manage the population beyond the park’s borders. There continues to be opposition from ranchers over concerns for livestock, despite the fact that only 2% of adult cattle deaths in 2015 were caused by predators, and of those only 4.9% involved wolves — less than half the number of cattle killed by dogs. Wolves beyond the boundary of the park are offered little to no protection: in Wyoming, wolves can be hunted freely across 85% of the state.