In 1995 Yellowstone began bringing back wolves; 30 years later young aspens returned, but the wider recovery remains uneven

Representative image of wolves in Yellowstone National Park (AI-generated) Three decades after wolves returned to Yellowstone National Park, young aspen trees are growing tall in parts of the park’s northern range for the first time in generations. The change has added fresh evidence to one of conservation’s best-known stories, but scientists say the results are more complicated than the popular version suggests.The United States began restoring wolves to Yellowstone in January 1995. Fourteen animals from Canada were brought to the park that year, followed by 17 more in 1996. In total, 31 wolves were relocated during the two-year programme. It was the first deliberate attempt to return a large predator to such a vast ecosystem in the country.The return of wolves changed how predators and prey interacted across Yellowstone. Elk numbers declined, while bears and cougars also played a part in increasing pressure on the herds. With fewer elk feeding on young trees in some areas, aspen shoots finally had a better chance of growing beyond the height at which they could be eaten.What happened after Yellowstone lost its wolvesWolves were once common in Yellowstone, but government predator-...