You might be among the 46 million people who’ve seen a video showing how wolves changed Yellowstone, or you may have heard some other version of this story. Yellowstone, which covers nearly 3,500 square miles of the western United States, was the world’s first national park. Its pioneering reintroduction of wolves, which began in 1995, set a worldwide precedent for conservation.
The first half of the story is well established. Wolves were eradicated from Yellowstone in the 1920s. With the wolves gone, populations of elk (a large species of deer) overgrew. Elk overgrazed the park’s riverbanks, turning groves of willow and aspen and beaver ponds into bare grasslands.
