While food security is most often cited as the reason for the recent interest in bison, tribes also hope that returning bison to the land will restore ecological balance. At Wolakota, for instance, bison have been eating the yucca plants that became plentiful after native grasses disappeared, tearing them up by the roots and allowing grasses to return. The grass regeneration increases carbon capture.

The bison also is tightly connected to the culture of Great Plains tribes such as the Sioux. The animals provided food, tools and shelter for Indigenous people, and some tribes consider them to be family.

“It’s a powerful feeling bringing our relatives home,” said TJ Heinert, Troy’s 27-year-old son, who lives on the Wolakota range with his family and helps manage it. On a recent winter morning he was dressed in camouflage as he prepared to hunt coyotes as part of a tribal benefit for his mother, who is recovering from cancer surgery.