WIND RIVER INDIAN RESERVATION On a sunny August day, Jason Baldes drove a mud-caked quad with a drink holder overflowing with matted buffalo fur toward the wild herd he has overseen since 2016. The day before, the Eastern Shoshone had killed one of the bulls, and the smell of warm blood and fresh meat still hung in the air. As we bounced over dirt clods, we passed the esophagus and pair of lungs that Baldes had left as a gift to the coyotes.

Every harvest from the growing herd marks a major victory for the Eastern Shoshone, whose untranslated name, Gweechoondeka, literally means buffalo eaters. But this one was special. For the first time in 139 years, the annual sun dance ceremony, a multiday ritual, would include buffalo meat a key ingredient that had gone missing since European settlers all but wiped the animals off the map in the late 19th century.

You cant have a sun dance without buffalo, Baldes said. You cant use a cow.

The buffalo appeared as we approached an interior fence nearing the western end of the property. Their patchy summer coats, shed almost to the skin to keep them from baking under the summer sun, gave them a half-naked look. A few bulls grunted, gurgled and chased one another in light sprints signs that breeding season had arrived. Most either lay bedded in the pasture or ambled along feeding.

The field, speckled with yellow-flowering pineapple weed, wasnt an ideal feeding spot for bison, who prefer grass. But for millennia the spaded hooves, concentrated grazing and wallowing of wild buffalo had shaped the ecosystem of the high plains. Baldes wanted to see whether simply setting the animals loose on the field would limit the invasives that had flourished over years of fallowing before seeding it with something else.

Buffalo are ecologically extinct, Baldes said. But theyre a keystone species ecosystem engineers. Theyre the best land managers if you allow them to do it.