The ecology of the Great Plains is diverse, largely owing to their great size. Differences in rainfall, elevation, and latitude create a variety of habitats including short grass, , and tall-grass prairies, and riparian ecosystems. The Great Plains extend from Mexico in the south through the central United States to central Canada. Many sub-regions exist within the area. The region is home to many animals, including American bison, pronghorn, mule, and white tailed deer, and birds such as ducks, hawks, and sparrows, along with many invertebrate species.