When the map documenting elk migrations in Greater Yellowstone was produced a few years ago by the Wyoming Migration Initiative, it made people realize the importance of landscapes unfragmented by development, across public and private lands, more than ever before. In the case of elk they move into Yellowstone National Park in spring and summer and then out to winter range, like lungs breathing in and exhaling. Similar maps could exist for lots of species, illustrating why Greater Yellowstone is compared to the Serengeti. But until the science is incorporated into planning efforts by cities and counties in Greater Yellowstone, the gauntlets of wildlife corridors will become only more perilous for the animals using them. Eventually, they can stop functioning.