Nor did Yellowstone’s early managers understand what would happen to an ecosystem without predators. Once the wolves were gone, the ungulate population in the park exploded, and the quality of the range quickly began to deteriorate. Overgrazed hillsides eroded, and stream banks denuded of woody shrubs began to crumble, damaging prime trout habitat. Elk browsing at their leisure, undisturbed by predators, decimated stands of young aspen and willow. Too many animals on the landscape brought starvation and disease, and the elk population followed a boom-and-bust cycle.
