The mammals of Florida are represented by approximately eighty native species. Nearly two-thirds of these forms are terrestrial, while the remaining one-third are aquatic. A very wide variability within species is characteristic of many Florida mammals. Some of the reasons for this include the great north-south expanse of the state and the associated range of temperatures, the historic fluctuations in sea level which have alternately isolated and rejoined populations of mammals, the extensive freshwater resources of Florida, and variety of shallow water coastal ecosystems. An example of a mammal showing wide variation is the old-field mouse, which is quite different in coat color and body shape throughout its range from the Panhandle through south central sections of the state. The present range of the armadillo in Florida is the result of both a natural extension eastward of a Louisiana population and northward movement of an escaped population that became established in central Florida in the 1930s.
