Keystone Species

These photographs show two keystone species of the American prairie--bison and prairie dogs. A keystone species is one that has a disproportionately large effect on its natural environment relative to its abundance. Keystone species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. In North America, the prairie dog and bison are considered keystone species. Prairie dog burrows provide nesting areas for mountain plovers and burrowing owls. Prairie dog tunnel systems also help channel rainwater into the water table to prevent runoff and erosion, and can also serve to change the composition of the soil in a region by increasing aeration and reversing soil compaction that can be a result of cattle and bison grazing. Prairie dogs stir up the soil around their burrows. Bison roll around those dirt areas to scratch off winter fur and coat themselves with soil to discourage insects. Constant use of the wallow can create a place for ephemeral pools which serve migratory birds with water to survive their migration. Bison grazing around prairie dog towns trim the grass so that prairie dogs are better able to see predators. Prairie dogs also eat the grasses around their burrows, allowing room for more plant growth and plants of higher nutritional value for themselves and the bison, pronghorn, deer, and bighorn that graze in their area. Poisoning and habitat destruction threaten prairie dogs and all that they support. When bison are unrestricted and able to graze freely on the grasses that they prefer, they help diverse plant species grow, aiding grassland recovery from drought, fire, and human use. I want my photographs to encourage viewers to learn about these creatures and their role in our world. A healthy prairie supports plants and animals which signal the health of the human environment as well.