Field Guide/Mammals/Northern Bog Lemming

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Synaptomys borealis (Northern Bog Lemming)
Family: Cricetidae [1]
Size: Average length overall: 4.7 inches (120 mm). Tail length: .8-.9 inches (21 to 23 mm). Weight: 0.77-.88 ounces (22 to 25 grams) [1]
Description: The northern bog lemming has reddish-brown fur that fades into gray on the under belly. It has noticeable ears that extend longer than the fur and has a very short tail.[1]
Similar Species: Similar in appearance to mice and voles but has a much shorter tail. The only way to distinguish the northern bog lemming from the southern bog lemming is by dental and skull characteristics.[1][2]

Range: Northern bog lemming can be found from Kansas, to Canada, and throughout northern states from Washington to Maine. In Minnesota they have been found in Lake of the Woods, Roseau, Koochiching, and Itasca counties.[2]
Habitat: Areas where moisture is high and grasses are present for food and shelter. They can be found in grass meadows within forests, wet meadows, bogs, tundra, and recently burned forest areas and typically inhabit an area less than one acre.[3]
Diet: The northern bog lemming consumes sedges, grasses, snails, slugs, and other invertebrates.[1][4]
Activity: They are nocturnal and diurnal. They create runways shared with other species by marking them with droppings. They remain active year around but spend summer months within burrows to avoid predators.[1][4][5]

Reproduction: The breeding season occurs from May to August. With a 3 week gestation period they have 2-3 litters per season with 2-8 offspring per litter. They are able to reproduce at 5 to 6 weeks of age.[2][4]
Lifespan: The average lifespan of a similar species, the Southern Bog Lemming is 2.4 years; though the lifespan of this northern variant remains unknown.[6]

Notes: Very little is actually recorded and known of this species which is hard to believe due to their reproduction habits and abilities. The northern bog lemming can have 2 to 3 litters in only a 4 month breeding season which seems like an impossible number, but the day after the females give birth they can breed again. Within the average 1 acre habitat, communities can range up to 36 lemmings. The extremely rapid breeding habits coupled with the low population density leads researchers to believe that there is a high mortality rate in the first year. The Minnesota Department of Natural Resources has developed concern for the lemmings scarcity. A Minnesota plan, Tomorrow’s Habitat for Wild and Rare, has listed the northern bog lemming as a species in need of great conservation.[1][2]
Northern Bog Lemming (this is the Southern Bog Lemming)

  1. a b c d e f g Northern Bog Lemming — Synaptomys borealis,, retrieved October 11, 2012) 
  2. a b c d Nordquist, Gerda, Northern Bog Lemming,, retrieved October 11, 2012) 
  3. Linzey, A.V.; NatureServe (Reichel, J.D. & Hammerson, G.)year=2008, "Synaptomys borealis", IUCN 2012. IUCN Red List of Threatened Species (Version 2012.1),, retrieved October 11, 2012 
  4. a b c Nicholas, Danielle (2001), "Synaptomys borealis", Animal Diversity Web,, retrieved October 11, 2012 
  5. Smithsonian National Museum of Natural History,, retrieved October 11, 2012) 
  6. Saunders, D.A. (1988), "Adirondack Mammals", IUCN 2012. IUCN Red List of Threatened Species (State University of New York, College of Environmental Science and Forestry): 216,, retrieved October 11, 2012