Duke is a cowboy. The buffalo are part of the largest conservation herd of bison in the United States. Every year, Duke organizes a roundup of theses buffalo to inspect the health of the herd and yield income to sustain the Nature Conservancy-owned ranch where the buffalo roam. It turns out that bison aren’t as easily herded as cattle, and a lot of cowboy mettle gets tested every year. Taken right into the action by filmmaker Alfredo Alcántara, we can all be thankful that we’re mounted atop nothing friskier than a theater seat when the thunder of the stampede turns our way.