Leaving the Map Behind

Bison, like these at Custer State Park, in South Dakota, were central to the Plains Indians. But when the U.S. National Parks Service tried to reintroduce them to Lakota lands, it tore the community apart. PHOTO: SARAH LEEN, NATIONAL GEOGRAPHIC CREATIVE

Rewilding is the idea that, having extirpated many species, by returning large animals and birds like the California condor to the landscape, we can restore key ecosystem functions.The most famous example is probably the reintroduction of grey wolves to the northern Rockies and the Mexican grey wolf to the desert Southwest in the mid-late’90s. There’s a phenomenon called trophic cascade, which means that a large predator like a wolf has a regulatory effect on the entire food chain. In Yellowstone, the return of wolves has meant that the elk can’t be fat and lazy and start to browse in a different fashion, which in turn allows aspen and beavers…