The large native mammals of the prairie are gone.  The pioneers who crossed the Great Plains recorded in their diaries seeing vast herds of bison, elk, bighorn sheep, and an occasional grizzly bear.  However, Euro-American settlers found it difficult if not impossible to live with free roaming herds of bison and elk.  These large ungulates were in competition with the settlers’ agricultural way of life.  The small acreage of the Monument and the intrusions of a state highway, three irrigation canals, and a residential development on the Monument’s east boundary all make the reintroduction of bison and elk impossible.  The Monument is home, though, to many species of smaller mammals.

The natural habitats at Scotts Bluff National Monument are home to 28 species of mammals.  However, the relatively small acreage of the Monument limits the number of individual animals (carrying capacity) that can be observed.  The largest mammals include mule deer, white-tailed deer, coyote, red fox, badger, striped skunk, common porcupine, and black-tailed prairie dog. The Nebraska Game and Parks Commission reintroduced bighorn sheep into the state owned Carter Canyon Wildlife Management Area located approximately 8 miles from the Monument.  It is hoped that bighorn sheep will migrate to the Monument and establish a resident herd.  Small mammals commonly observed by visitors include eastern cottontail, desert cottontail, and evidence of the eastern pocket gopher.  These animals excavated dirt from their burrows and push the soil to the surface where it lays on mounds on top of the ground.  By far the most numerous mammal species are the mice and voles which are seldom seen by visitors, but these small mammals provide a food source for larger mammal carnivores and predatory birds.