The broad palette of plant life sustains a bountiful wildlife population in the park. Large grazing mammals including bison, pronghorns, and wild horses can often be found eating grasses. Deer and elk graze in the grasslands and browse on woodier plants. Smaller mammals like cottontail rabbits, least chipmunks, voles, and mice feed on the plants and the berries and seeds the plants produce. Prairie dogs have a noticeable effect on the plants near their towns, fostering the growth of fast-growing forbs over other plants because of the rodent's continuous grazing.