The saddleback pattern
Among North American shrews this one is comparatively easy to recognize. It is on the larger side for the genus, about 4 to 5 inches with the tail, and sharply three-toned: nearly black down the back, brownish-gray on the sides, and pale gray below. That contrast earns it the old names blackback shrew and saddlebacked shrew. Most similar shrews in its range are a more uniform brown.
Two close relatives complicate the map. The tundra shrew was once treated as a subspecies of the Arctic shrew, and the maritime shrew of the Canadian Maritimes has been proposed for full species status. Both sit outside the US range covered here, but they explain why older books describe “the Arctic shrew” with a much broader distribution than the species holds today.
Cold-country ground cover
This is a shrew of the north woods and their edges: damp forest floor, brushy clearings, sedge meadows, and the grass along northern lakeshores. It hunts insects and other small invertebrates through leaf litter, active in bouts around the clock in the shrew manner, eating often to keep its furnace stoked.
Winters don’t stop it. Like all shrews it stays active year-round, foraging under the snowpack where temperatures hold near freezing. Reports still cluster in the warmer months, because that is when traplines run and cabins open. The summer bulge in the record is a fieldwork bulge; the animals are out there in January too, just uncounted.
South edge of a northern range
Despite its name, the Arctic shrew’s US footprint is the upper Midwest. Minnesota holds the largest share of records, followed by Michigan and Wisconsin, with North Dakota, Montana, and South Dakota trailing. The species reaches far across Canada and Alaska, and the US states are simply the southern rim of that vast northern range.
Secure, with a naming shadow
The IUCN lists the Arctic shrew as Least Concern, and nothing suggests broad decline. The main caution for anyone reading records is taxonomic: older specimens and checklists may lump in animals now placed in the tundra or maritime shrews, so historical range maps sometimes show a broader US presence than current names support. Within its midwestern stronghold it remains a standard member of the forest-floor community, more often caught in a survey trap than seen alive.
