From National Geographic:

Twenty-five years after gray wolves returned to Yellowstone National Park, the predators that some feared would wipe out elk have instead proved to be more of a stabilizing force. New research shows that by reducing populations and thinning out weak and sick animals, wolves are helping create more resilient elk herds.

For the past 12 years, elk numbers in the park’s largest herd have leveled off between about 6,000 and 8,000, instead of extreme boom-and-bust cycles due to climate fluctuations.

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