Bison March—In Mono

As Yellowstone’s harsh winter grips ever tighter, this dominant female bison leads two bulls, and a host of stragglers, from the deep interior of Hayden Valley on a march to the more forgiving valleys of the Madison River plateau and the geyser laden springs found in the Firehole River corridor. Bison do not migrate south for the winter, instead small herds and solo bulls move to lower elevations where they can plow the snow with their muscular heads, sweeping left and right, to reach the grass beneath.