Rut in Hayden

In Hayden Valley, the summer bison rut fills the air with grunts, rumbles, and roars as hundreds of bison mill restlessly during one of nature’s most spectacular reproduction rituals. Adult bull bison chase a lone cow, each determined to be chosen for mating, while young bison remain around the edges watching and learning. A bull tends a cow by shielding her from other bulls until she allows mating, and a rival bull may bellow for her attention as the tending bull roars back, sometimes leading to a brutal battle. In April and May, rusty red calves dot the valley as adult female bison give birth every one to two years and nurse a calf for a year, and a baby bull born early in spring often grows into a larger, more dominant adult. Bison also wallow in dusty pits to dislodge biting flies and other insects from their fur, while large bulls may paw the dirt and horn the wallows in displays of aggression.

Wyoming · United States