Yellowstone's iconic bison herds have merged into a single entity after 100 years of wandering the park

A group of bison walking in the center of a main road.

Bison in Yellowstone National Park spent over 100 years as two genetically distinct herds. But now they're roaming as one interbreeding population, a new study suggests.

Herds of wild bison (Bison bison) have meandered through Yellowstone's vibrant landscape since prehistoric times. Grazing freely in the expansive grasslands of the park, these are the last free-range bison in the United States.