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

Northern bog lemming, Synaptomys borealis, study skins in the collections of the Illinois State Museum, Springfield. 

Rodentia (Rodents)
Cricetidae (Lemmings and Voles)

Length: 110-140 mm (4.3-5.5 in)

Weight: 27-35 gm (0.95-1.23 oz)