Thirty years ago, park rangers reintroduced grey wolves into Yellowstone National Park. They wanted to restore the ecosystem and get the elk... How the wolf changed Yellowstone 30 years after ...

Over the last three decades, Yellowstone National Park has undergone an ecological cascade. As elk numbers fell, aspen and willow trees thrived. This, in turn, allowed beaver numbers to increase, ...

A new study shows how wolves steal kills from cougars in Yellowstone, driving an uneven feeding rivalry and changing cougar ...