Perognathus longimembris
(Little Pocket Mouse)

Description:
The little pocket mouse is indeed, a small mouse. It occurs in variable colors, the upper body is often yellowish to buff color with some darker, interspersed hair. The ventral side is either buff or brownish. Their coloration seems to somewhat approximate that of the soil they live in. They have a small, white patch at the base of each ear. Total length is about 4 inches to 5 7/8 inches (110-151 mm) and their tail length is just over 2 to 3 3/8 inches (53-86 mm). The tail is not striped, but a uniform brownish color.

Range:
From southeastern Oregon and southwestern Idaho, south to Baja California and northwestern mainland of Mexico.

Habitat:
Found in sagebrush, creosote bush, and cactus communities. On slopes with widely spaced shrubs, found in firm, sandy soil overlain with pebbles. In Idaho, found in shadscale/dwarf sage on lower slopes of alluvial fans in Raft River Valley.

Diet:
Feeds primarily on seeds.

Ecology:
This species is smallest rodent in the Pacific Northwest. The little pocket mouse remains in its den during severe weather and it may enter a state of torpor when inactive. Torpor lowers its metabolic rate considerably and thus saves energy. In Idaho, it is inactive during the winter months, and there is some evidence that it hibernates. If it does hibernate, it is the smallest mammal to do so, with the exception of bats. In southeastern California, it is known to hibernate up to 6.5 months. It is typically nocturnal. In the spring it is most active 2 to 5 hours after sunset, with a second peak just before sunrise. It is able to metabolize water from its food like most members of this family of rodents. It is primarily solitary. Populations may fluctuate markedly from year to year and seasonally. In some areas, such as the desert of Nevada, this species is most abundant mammal; populations have been estimated to be as high as 400 per 0.4 ha (1 acre).

Reproduction:
Female produces 1-2 litters of 3-7 young/litter. Young are born April-July. Species may not reproduce in years with below average precipitation.

Conservation:

Status:	Protected nongame species
Global Rank:	G5
State Rank:	S1

Important State References:
Larrison, E.J. and D.R. Johnson. 1973. Density changes and habitat affinities of rodents of shadscale and sagebrush associations. Great Basin Natur. 33:255-264.