The western harvest mouse is a plains and grassland animal, and Wyoming’s records match that geography. Reports come from sixteen counties, but they concentrate east of the mountains: Johnson, Campbell, Sheridan, and Hot Springs counties along the dry flank of the Big Horns, plus Laramie, Goshen, and Platte in the southeast prairie. The high country of the northwest contributes almost nothing.
Reports build from June to a July peak and taper by October, a pattern that fits both the mouse’s breeding season and the summer field-work calendar. Winter records exist but are sparse, which says more about trapping effort in cold months than about the mice, who stay active under the snow.
NatureServe ranks the species S5, secure, in Wyoming, and the breadth of the record supports it. This is a mouse of tall grass, weedy field edges, and marsh borders, habitat the state’s rangeland still holds in quantity. The record here reads as genuinely widespread, not just well-sampled.
Full species profile
