For Michael Nichols, National Geographic’s longtime staff photographer and photo editor at large ... Grand Canyon of the Yellowstone. Rutting bison joust in Yellowstone’s Lamar Valley.

For his first year as a National Geographic Society photography fellow, Guttenfelder worked throughout the ecosystem. He regularly posted Instagram photos ... A Yellowstone bison held temporarily ...

Editor’s Note: This story accompanies the May 2016 issue of National Geographic magazine ... Two of Yellowstone’s iconic species, bison and elk, spill seasonally—and naturally—beyond ...