The Scientist: Can Rewilding Large Predators Regenerate Ecosystems?

Image: Matias Rebak

In the absence of firm evidence, conservationists have been eager to interpret early predator reintroduction studies—largely based on the purported regenerative ecological effects of returning gray wolves (Canis lupus) to Yellowstone National Park in the mid-1990s—as a rationale for bringing predators back to many parts of the globe. In Colorado, for instance, conservation organizations have been using such findings to push for the approval of a bill on the November ballot that would effectively mandate wolf reintroduction in the state to restore the ecosystem’s “natural balance.” But some ecologists caution that the ecological outcomes of such projects are unclear. 

In search of answers, scientists are employing novel approaches to study the ecological roles of large carnivores, from the African savannah and the Andean plateau to the ocean, and to understand how ecosystems change as they are lost or reintroduced. What they’re finding is that predators have powerful, yet nuanced and complex effects that ripple through food webs in what are known as trophic cascades—effects that depend not only on the nature of the hunter itself, but also on characteristics of its prey and the habitat the animals share. 

“There’s still good reason to believe that trophic cascades will . . . occur in many systems,” Smith says. “It’s just that we don’t really have all the data yet to understand exactly when, where, and why.”

Read the full story at The Scientist