In summer, pronghorn may be the only large mammals visible in this valley, but in winter the wildlife picture changes dramatically as herds of elk and bison, mule deer, and bighorn sheep descend from the snowy high country to look for food. Gardner River Valley lies at the lowest elevation in the park, where even in midwinter grasses are often still visible above the snow. Wildlife sightings here are tied to season and habitat, and pronghorn remain past June because the summer vegetation provides ideal camouflage for females raising young.