‘Rewilding’ may help restore landscapes

Poisonings and unregulated hunting obliterated nearly all of the gray wolves from Canada to Mexico, their original home range.

Then the reintroduction began.

Since their reintroduction to Yellowstone National Park and Idaho in the 1990s, gray wolves have done so well they’re reclaiming other parts of the northern Rockies.

In the places where they returned, wolves tidied up explosive deer and elk populations, which had eaten valleys barren. That helped bring back trees and shrubs. Birds and beavers, as well as the animals that live in dams, also returned. The wolves ate coyotes, freeing up their prey for others. Bears and raptors came back for carrion. With more trees controlling erosion, the flows of some rivers were less chaotic, forming pools that became new habitats.

“We’re just uncovering these effects of large carnivores at the same time their populations are declining and are at risk,” said William Ripple, an ecologist at Oregon State University. He’s found that if you reintroduce some carnivores, or return them back to lost ranges, a cascade of ecological bounty may follow.

But not always. Nearly half of carnivore reintroductions fail, and understanding where they may or may not work is critical to getting it right.

Lions and tigers and bears — along with gray wolves and 21 other species of large, terrestrial carnivores — roam this planet. Extinction and declining populations threaten most of them. Recently, scientists and conservationists have been hoping that reintroduction will result in ecological benefits like those seen with gray wolves.

So, Ripple and Christopher Wolf, a postdoctoral researcher in his lab, analyzed hundreds of potential sites from a database of protected areas around the planet where large carnivores have disappeared. They focused on big places with small human footprints, available prey and buffer zones where animals may traverse safely. Their analysis revealed 130 potential sites suitable for reintroduction and an additional 150 spots with little human activity to consider preserving. Their results, published recently in Royal Society Open Science, suggest with proper attention and care to ensure these carnivores’ survival, reintroduction programs could restore lost ecosystems worldwide.

But it won’t be as simple as finding a dot on a map.

Their paper mentions just two specific reintroduction sites where reintroduction would likely work. They suggest it could be possible to put gray wolves in Olympic National Park in Washington and sending endangered red wolves, which once roamed the southeast, into Everglades National Park. These places have space for reproduction and development, prey and humans who may tolerate them.

But for many other locations, especially in developing countries, people still hunt some animals for bushmeat or body parts used in traditional medicine. Fences limit range. Humans compete for prey or kill carnivores that threaten their lives, agriculture or livestock. Not all corridors are safe.

The biggest hurdle will be finding humans willing to live alongside and support efforts to keep big carnivores around, said Thomas Newsome, an ecologist studying human-predator interactions at the University of Sydney who was not involved in this study.