Sigmodon arizonae arizonae, the Arizona cotton rat, is an Extinct subspecies; the Colorado River cotton rat, S. arizonae plenus, is Near Threatened.
| All cotton rats have a strong connection with grass, which they feed upon, and in which they construct their runways. Within their range in southeast and central Arizona and western Mexico, Arizona cotton rats inhabit only grassy areas where there is enough water to support grasses, weeds, or brush. They are common around ponds and in irrigated fields. They give birth to fully-furred young who can run around within a few hours after they are born. Population booms sometimes occur shortly after periods of rain.
Mearns, E.A., 1890. Bulletin of the American Museum of Natural History, 2:287.
Mammal Species of the World