More wolves, it seemed, meant more beavers, but that wasn’t all: the return of Yellowstone’s top predator was having repercussions up and down the park’s food chain. The Lamar Valley that O-Six claimed as her own was not the same landscape that her Druid ancestors had been introduced to fifteen years before. It was healthier in ways that even some of the wolf’s most ardent advocates hadn’t anticipated. Biologists called this type of chain reaction a trophic cascade,
