In 1926, the last remaining wolves were killed in Yellowstone National Park. It was the outcome of a centuries-long campaign to rid North America of its wolf population.

Wolves were viewed as a nuisance. They killed valuable livestock and created a barrier against our drive to conquer the West. Our bid to eradicate them was swift and effective but carried unexpected consequences.

In Yellowstone, removal of the wolves resulted in reduced pressure on the elk population, triggering a cascade of ecosystem-wide devastation. The growing elk herds decimated willow, aspen, and cottonwood plants, which caused beaver populations to collapse. This cascade of events changed the trajectory and composition of the park’s rivers as banks eroded and water temperatures rose from reduced vegetative cover. As a result, fish and songbirds suffered.

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