Pocket Mouse, Pocket Mice

Heteromyid rodents family includes kangaroo mice, kangaroo rats, and pocket mice. These are delicate mice with thin bones and a narrow, mouselike skull with a huge enlargement at their ear bones, an adaptation that allows them to detect the sound of approaching predators. All 20 or so species of pocket mice are found in dry regions west of Mississippi. Similar in general appearance and habits (all are active only at night), they vary in size, color, and the texture of their fur. Pocket mice are bounders. They have enlarged hind feet that propel them along in leaps of a yard or more.

Pocket mice are small enough to fit in a coat pocket, but their common name actually comes from their fur-lined cheek pouches, which they use to transport food. Like pants pockets, these cheek pockets can be turned inside out for food removal and cleaning.

Total Length: 4.5-5.7 in.; tail: 2.2-2.6 in.
Habitat: open grasslands with sandy loam; also found on the edges of aspen parklands

Weighing only one-quarter to one-third of an ounce, the Olive-backed Pocket Mouse is one of the smallest North American rodents. Perognathus refers to the fur-lined pockets on the outside of the cheeks, where it stores and carries food; fasciatus means band or girdle. It is a resident of dry sandgrass prairie, especially where the soil is sandy and there are bare areas. It makes shallow burrows through the light sand. The pocket mouse often takes sand baths, which may reduce its skin parasite loads.

The Olive-backed pocket mouse and other pocket mouse species build summer nests roughly 1 to 2 feet below the surface. They go into a torpor during cold weather but are not deep hibernators and rely on caches of stored seeds to get through the winter. They obtain all their water from these seeds. Their diet mainly consists of seeds, but they also take various insects.

Hispid Pocket Mouse

The Hispid Pocket Mouse (Chaetodipus hispidus, also known as Perognathus hispidus) is the largest of the pocket mice. The Hispid Pocket Mouse is widespread on the Great Plains and in the southwest, from prairies to oak or pinyon-juniper woods, wherever there is a good understory of grass. It has a long bicolor tail that is thin at the tip. Olive-brown above and white below, with distinct buffy stripe on sides. "Hispid" means coarse or bristly.

Olive-backed Pocket Mouse (Perognathus fasciatus)

References:
1. Mammals of North America by Adrian Forsyth
2. North American Wildlife Reader's Digest
3. Mammals of North America (Kaufman Focus Guides) by Kenn Kaufman, Rick Bowers, Nora Bowers