Its range overlaps with the other species in genus Synaptomys, the northern bog lemming, in southeastern Canada, but extends farther south.

Southern bog lemmings are covered with thick, brownish fur on their backs that ranges in color from reddish to dark brown and have a grizzled appearance.

The shallow-grooved upper incisors and a relatively shorter tail distinguish this species from other rodents.

Females have six teats, which distinguishes this species from its closest relative, northern bog lemmings, which have eight.

The grassy openings and edges of these forests, especially where sedges, ferns, and shrubs grow and when the soil is loose and crumbly, are habitats the bog lemming prefers.

The southern bog lemming creates a maze of interconnecting tunnels and runways and builds nests from plant fibers.

[4] Fresh vegetation, especially the leaves, stems, seeds heads, and roots of grasses and sedges is the main food of this species.

Raspberries, blueberries and other fruits, insects, fungi, and bark form a lesser part of the diet.

The range of these animals is thought to be declining in some areas due to loss of wetland habitat.