South Dakota’s 137 records for the southern red-backed vole are really two stories. The bigger one is the Black Hills: Lawrence, Pennington, and Custer counties together hold 104 records, with the Black Elk Wilderness alone accounting for 22 and the broader national forest adding 9. The smaller story sits clear across the state, where Marshall and Roberts counties in the glaciated lake country of the northeast contribute 23 more.
A forested island rising from the prairie
The Black Hills concentration makes biological sense. This vole needs cool, shaded forest floor, moss, leaf litter, and rotting logs, and in South Dakota that combination exists in real depth only in the Hills, a timbered island hundreds of miles from the species’ northern heartland. Custer State Park, Wind Cave National Park, and the national forest’s higher reaches all hold that kind of ground. The northeastern cluster shows the species isn’t confined to the Hills, though whether those records mark a second stronghold or simply a second survey site is what record counts alone can’t settle.
A tight summer crest, and a steady grade
The calendar here is sharp: 65 records in July and 51 in June, then a fast drop to 10 in August and almost nothing after. That reads as survey season in the Hills, since the vole itself stays active under snow all winter. NatureServe ranks the species S4 in South Dakota, apparently secure, and it carries no separate state listing.
Full species profile
