She watches us calmly with her big, brown eyes as we approach the pen in the middle of a pasture scattered with spiky Douglas firs, juniper trees, and light-green sagebrush. The Big Belts, a Rocky Mountain hill range in western Montana, rise around the field, and the waters of Canyon Ferry Lake glimmer on the horizon. Matt Elvbakken, the man hired to kill the 900-pound bison, is wearing camouflage rubber boots, a camouflage t-shirt, and a camouflage baseball cap. He crouches down and looks her straight in the eye. A long, yellow Winchester .243-caliber rifle rests in the crook of his sunburnt arm. “It’s just not your day,” Elvbakken says to the animal.