A lone bison in Yellowstone, cradle of American conservation. Among all the wonders of Greater Yellowstone, wildlife is what sets our ecosystem apart from the Colorado Rockies, Sierra, Wasatch and most other parts of the US. Seldom, however, do we reflect on the reasons why the diversity and health of charismatic megafauna is still able to persist here. Each of us needs to ask ourselves what we'd be willing to do—and do without—to give animals the space they need to survive as epic challenges converge. Photo courtesy Jacob W. Frank/NPS