Effects of reintroducing top predators questioned

Date:  April 3, 2019

Source:  University of Wyoming

For years, scientists have assumed that when top predators are reintroduced to an ecosystem, the effects are predictable: The ecosystem will return to how it was before the predators were wiped out.

Now, University of Wyoming researchers have published a study showing that there's little evidence for such claims. This has big implications for wildlife conservation in places such as Yellowstone National Park.

Most people are probably familiar with the story of Yellowstone's wolves. Wolves were wiped out in Yellowstone in the 1920s and, in their absence, elk became much more common and ate so much vegetation that it degraded the ecosystem.

Wolves were reintroduced to Yellowstone in the mid-1990s and over the next two decades brought profound change to the ecosystem. The number of elk decreased, while the number of aspen, willow and cottonwoods increased. Biologists observed positive responses by other animals, from songbirds to beavers. Scientists assumed that Yellowstone's ecosystem is on its way to being restored to historical conditions.

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