Eight records, one county, one season: Wyoming’s cliff chipmunk file is as narrow as they come. All eight reports come from Sweetwater County in the southwest, and six of them landed in September. The cliff chipmunk is a canyon-country animal at heart, at home on the redrock of the Colorado Plateau, and southwestern Wyoming’s juniper breaks and sandstone rims are the northern fringe of its world.
A September weighting like that points to one or two survey pushes rather than a seasonal habit. Chipmunks are active by day and conspicuous about it; they don’t hide from an observer the way a marten or a shrew does. So the small count likely means the suitable rock country in Wyoming is small and rarely walked, not that the chipmunks are especially secretive.
NatureServe ranks the species critically imperiled in the state, a ranking that reflects the tiny documented footprint. The most recent report is fresh, from May 2026, which shows the animal is still being found on that southwestern rim. What the record can’t yet say is whether Wyoming’s cliff chipmunks are a stable fringe colony or a handful of animals hanging on at the edge. A few autumn days of survey work in Sweetwater County’s rock country would go a long way toward an answer.
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