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Synaptomys cooperi Baird, 1858
Southern Bog Lemming
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: SU
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Data Deficient
Element Occurrences (EOs) in Georgia: 1
Habitat Summary for element in Georgia: Bogs, marshes, meadows, and upland forests with thick humus layer
Dorsal pelage varies from bright chestnut to dark reddish brown. The venter is light silver to gray. The tail is short and bicolored, and barely longer than the length of the hind foot. There are five toes on the front and back feet. Females have six mammary glands, in contrast to the eight found on northern bog lemmings. They have a total length of 110 – 154 mm (4.3 – 6.1 in), a tail length of 13 – 25 mm (0.5 – 1 in), hind foot length 16 – 24 mm (0.63 – 1 in), ear 8 – 14 mm (0.3 – 0.6 in), and a weight of 20 – 50 g (0.7 – 1.8 oz).
The southern bog lemming is often mistaken for the northern bog lemming (S. borealis) but can be distinguished by the number of mammary glands. The Southern Bog Lemming is most readily distinguished from similar species by its short tail, which is approximately the length of the hind foot.
he Southern Bog Lemming occurs in a wide variety of relatively open habitats, including grasslands, mixed deciduous or coniferous forests, spruce-fir forests, glades, old fields, meadows, freshwater wetlands, and high elevation forests in the southern Appalachians. Southern bog lemmings construct surface runways and underground burrows where they make their nests in saturated soils. These burrows are usually located under coarse woody debris. Their presence can be indicated by fresh grass cuttings and bright green feces in the runways. Their home range is typically 0.3 hectares or less.
outhern bog lemming prefer leaves, shoots, roots of grasses and sedges, particularly of bluegrass (Poa), white clover (Trifolium repens); along with fruits like blackberries (Rubus spp.) and blueberries (Vaccinium spp.) and some fungi. Their droppings appear light green due to the high quantity of vegetation they consume. Southern bog lemmings also eat invertebrates such as slugs, snails and beetles.
This species breeds year-round, and is higher during warmer months and depressed between November and February. Females are polyestrous and can produce 2 or 3 litters per year. Gestation lasts for 23–26 days; means litter size approximately four. Young are born between April and September and weigh 3.7 g at birth on average. They are weaned in 2-3 weeks and are born with no fur, blind, and with the ear pinnae folded over. Their claws are apparent at birth. They are fully furred by the first week, and their eyes open at about 12 days of age. Male southern bog lemmings reach sexual maturity in 5 weeks but most individuals will breed before they reach their maximum size. The average lifespan of the Southern Bog Lemming is a short 8-12 months, although individuals living over 2 years have been reported. Southern bog lemmings use burrow systems about 15 to 30 cm deep as well as surface runways located among roots of shrubs or underneath mosses. They may use runways and tunnels of other species but usually create their own. These runways are 2.5-5 cm in diameter and are found in heavy vegetation. In wooded areas, they occasionally make the runways by pushing up leaf mold. They are active throughout the day and night, but peaks of activity occur mostly in the afternoon and night. They are active throughout the year, and activity is limited when the temperature reaches below -7 ˚C. Southern bog lemmings can live in groups of up to twelve individuals. They communicate with each other with scent markings from anal secretions and squeaking vocalizations. Southern bog lemmings have many predators including owls, hawks, red foxes, gray foxes, domestic dogs, badgers, weasels, snakes, bobcats and house cats.
The species is difficult to catch and is often underreported in small mammal surveys. The most successful method of capture that has been documented is using modified Fitch live traps.
The Southern Bog Lemming ranges from southeastern Canada to western Minnesota and southward into Kansas, northern Arkansas, Tennessee, North Carolina, Virginia, Maryland and Georgia in the United States. Within Georgia, the southern bog lemming is restricted to the extreme northeast corner.
They are federally listed as least concern due to their wide distribution, however, deforestation, climate change, elimination of native grasslands, or development of roadways could eliminate bog lemming habitat. Historically, the southern bog lemming has been the dominant microtine rodent in forest clearing habitats, but within the last 15 years, the meadow vole (Microtus pennsylvanicus) has expanded its range southward and become the most abundant. Southern bog lemmings have become rarer since the arrival of M. pennsylvanicus, possibly due to competition for resources and habitat.
This species is ranked as critically imperiled in Georgia.
Maintaining woodland openings, bogs, meadows, and montane grassy fields with periodic mowing, haying, or grazing would benefit the southern bog lemming populations in general. However, they showed negative short-term response to prescribed burning. Making connections to habitats that allow expansion or establishment of meadow voles should also be avoided. Habitat preferences and distributions are poorly understood for this species. Campbell et al. 2010 study suggests that this species is more common within the Southeast than previously documented. Efforts to more effectively survey for this species will better inform managers the extent of their range.
Campbell, J. W., M. T. Mengak, S. B. Castleberry, and J. D. Mejia. 2010. Distribution and status of uncommon mammals in the Southern Appalachian Mountains. Southeastern Naturalist 9:275-303.
Wilson, G. M., and J. R. Choate. 1997. Taxonomic status and biogeography of the southern bog lemming, Synaptomys cooperi, on the central great plains. Journal of Mammalogy 78:444-458.
Krupa, J. J., and K. E. Haskins. 1996. Invasion of the meadow vole (Microtus pennsylvanicus) in southeastern Kentucky and its possible impact on the southern bog lemming (Synaptomys cooperi). American Midland Naturalist 135(1):14-22.
Linzey, A. V. 1984. Patterns of coexistence in Synaptomys cooperi and Microtus pennsylvanicus. Ecology 65:382-393.
IUCN. 2009. IUCN Red List of threatened species. Version 2009.1. (International Union for Conservation of Nature and Natural Resources).
Wetzel, R. M. 1955. Speciation and dispersal of the southern bog lemming, Synaptomys cooperi (Baird). Journal of Mammalogy 36:1-20.
Pacifici, M., L. Santini, M. Di Marco, D. Baisero, L. Francucci, G. G. Marasini, P. Visconti, and C. Rondinini. 2013. Generation length for mammals. Nature Conservation 5: 89-94.
Patton, T. H. 1963. Fossil remains of southern bog lemming in Pleistocene deposits of Texas. Journal of Mammalogy 44:275-277.
Rose, R. K., and L. J. Ford. 2012. Minor species as the dominant rodents in an oldfield. The American Midland Naturalist 168:1-9.
Trani, M. K., W. M. Ford, and R. Brian. 2007. The land manager's guide to mammals of the South. The Nature Conservancy, Durham, North Carolina. 381-384
Fabiola Clermont
F. Clermont, November 2017: original account
M. MacKnight, December 2018: Updated information
P. Sirajuddin, April 2019: Updated information and edited format
S. Krueger, Jan. 2020: added photo credit