| White-eared Cotton Rats are small to medium-sized for the genus, with conspicuous white ears and hairy tails. Males and females are the same size. They inhabit moist pine-oak mountain forests. Cotton rats of different species apparently do not share territories. Sigmodon ochrognathus, the Yellow-nosed Cotton Rat, is found in some of the same mountains, but at different elevations, in drier habitat. Where White-eared and Tawny-bellied Cotton Rats both occur, Sigmodon fulviventer, the largest and apparently dominant species, inhabits open grassland and its white-eared cousin is forced onto rocky, brushy slopes. Like all cotton rats, it eats grass and builds nests and burrows. Where it lives in grassland, runways through the grass are evidence of its presence.
Head and Body: 132-157 mm
Bailey, V., 1902. Proceedings of the Biological Society of Washington, 15:115.
Mammal Species of the World
Mammalian Species, American Society of Mammalogists' species account