With more than seven thousand mapped reports across twenty-six counties, the northwestern deer mouse is one of the most frequently recorded mammals in Washington. Even so, the map’s hot spots deserve a skeptical read. Skamania County alone holds nearly half the records, a signature of intensive small-mammal study along the Columbia River Gorge and the south Cascades rather than proof the mouse is scarce elsewhere. This is an animal of forest floor, clearcut, alpine meadow, and shoreline driftwood alike, and a low county tally usually means low looking.
The yearly pattern is a clean arc. Reports build from May, crest in July, and stay heavy through September before dropping off with the first mountain snows. Summer brings both peak mouse activity and peak human traffic on the trails, and the record mixes the two.
NatureServe calls the mouse apparently secure in Washington, ranked S4, and nothing in the record argues otherwise. From the Olympic rainforest to Mount Rainier’s subalpine meadows, it turns up almost anywhere someone sets a trap or lifts a log.
Full species profile
