Every one of Washington’s 1,176 Great Basin pocket mouse records sits east of the Cascades. Walla Walla, Benton, Grant, and Franklin counties lead, and the map reads as a roll call of shrub-steppe: the Juniper Dunes Wilderness Area, the Columbia Basin, L.T. Murray, Wells-Chelan-Sagebrush Flats, and Wenas wildlife areas, and Ginkgo Petrified Forest.
A night-shift seed collector
This small mouse carries the dry country in its name and its habits. External fur-lined cheek pouches let it stuff seeds where they stay dry, then haul them back to burrow caches, and it favors the loose, sandy soils of sagebrush country where digging is easy. It works almost entirely at night, emerging after dark to forage under the shrubs and slipping back underground before dawn.
Underground for the cold months
Pocket mice retreat into their burrows and sleep through the harshest part of winter on their cached seeds. Washington’s counts fall to nearly nothing in January, build from March as the animals emerge, and crest in July, when adults and new juveniles are most active on warm nights.
Status in Washington
NatureServe ranks the Great Basin pocket mouse S5, Secure, in Washington, and the species is native to the state. USGS NAS does not list it as nonindigenous here.
Full species profile
