Every one of Wyoming’s sixteen canyon mouse records comes from Sweetwater County, the sagebrush basins and badlands of the state’s southwest corner. For a rock-loving mouse whose range runs through the canyon country of Utah and the Great Basin, southwestern Wyoming is the last stop north, and the state’s record couldn’t show it more plainly.
Stranger still is the timing. Half the records are from January, with February adding more, in a state where most small-mammal work waits for summer. Winter records like that come from deliberate effort: researchers checking talus and crevice roosts, or captures from winter trap lines in the desert basins. The canyon mouse doesn’t hibernate, so a January mouse is simply a mouse going about its life under the snow-covered rock.
NatureServe ranks the species critically imperiled in Wyoming, a ranking built on that single-county footprint. It’s worth holding both ideas at once. The mouse may be genuinely localized here, at the cold edge of what it can tolerate. It may also be under-searched, since Wyoming’s desert southwest sees far fewer mammalogists than its famous parks. Either way, Sweetwater County currently carries the state’s entire known population, which makes any new record from anywhere else in Wyoming a meaningful find.
Full species profile
