Related Biomes
Northern Bog Lemming
Northern Bog Lemming, Synaptomys borealis
The northern bog lemming is the rarer of two species in the genus Synaptomys, and, as their name suggests, they have a more northerly distribution than the more common southern bog lemming (Synaptomys cooperi). Superficially, the two species are very similar in appearance, and where their ranges overlap, they are most easily distinguished by distinct differences in tooth morphology. This is particularly useful given that during the late Pleistocene, Synaptomys borealis occupied much of the current range of their southern cousins. It appears that as the ice sheets retreated, Synaptomys borealis migrated northward and were replaced within much of the central and eastern U.S. by Synaptomys cooperi. The association between northern bog lemmings and colder habitats makes them an important cold-climate indicator, and their presence in the central U.S. during the Late Pleistocene suggests that this region was much cooler during the last glaciation.
Northern bog lemming, Synaptomys borealis, study skins in the collections of the Illinois State Museum, Springfield.
Length: 110-140 mm (4.3-5.5 in)
Weight: 27-35 gm (0.95-1.23 oz)
Physical Description:
Northern bog lemmings are short, stocky rodents with verys hort tails, grayish brown or brown colored fur with a light orange patch at the base of the ear, and grooved upper incisors.
Northern bog lemmings prefer wet, open habitats and are typically found in boreal forests, bogs, black spruce swamps, tundra and moist alpine meadows across Canada and the extreme northern U.S. They appear to prefer habitats dominated by sphagnum moss, ericaceous shrubs and graminoids (Foresman 2001).
Synaptomys borealis is primarily an herbivore with a preference for sedges and grasses, although this rodent will also eat snail, slugs and insects (Foresman 2001).
Northern bog lemmings are active year round and during both day and night. They are fairly social animals and live in small colonies. As with many rodents, they construct surface runways, often below leaf litter, as well as nests that are concealed under vegetation or surface structures, such as logs, or that are located in shallow underground burrows. The nests are often constructed from sedges, grasses and mosses.
During the Late Pleistocene, Synaptomys borealis occupied much of the central and eastern U.S. south of the Laurentide ice sheets, which is much further south than its current range. Remains of this species have been recovered from Wisconinan sites as far south as central Nevada, Kansas, northern Arkansas and northern Tennessee.
As the continental ice sheets retreated northward towards the end of the Pleistocene and climates in the central U.S. warmed, northern bog lemmings migrated north, following the boreal forests. They were replaced within much of the central and eastern U.S. by the southern bog lemming (Linzey 1983).
Northern bog lemming remains have been recovered from late Pleistocene paleontological sites scattered across the Midwest. These include sites in Arkansas (Peccary Cave), Missouri (Bat Cave and Crankshaft Cave), Iowa (Craigmile and Eagle Point), Wisconsin (Moscow Fissure), Ohio (Sheriden Pit) and northern Tennessee (Robinson Cave, Guy Wilson Cave and Baker Bluff Cave).
Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammalogists, Special Publication 12:1-278.
Linzey, A. 1983. Synaptomys cooperi. Mammalian Species 210: 1-5.
Related Animals:
