The Dismal Swamp subspecies of the Southern bog lemming, Synaptomys cooperi helaletes, was named based on specimens collected during the 1895-1898 biological surveys conducted in the Dismal Swamp by the US Department of Agriculture. Unknown in the 20th Century until re-discovered in 1980, this small boreal rodent was believed to be restricted to the Great Dismal Swamp of Virginia and North Carolina where the cool damp conditions had permitted it to survive during the Holocene. However, field studies conducted since 1980 have revealed southern bog lemmings to be widespread throughout southeastern Virginia, with populations encompassing an area of more than 3300 km2, including the cities of Virginia Beach, Chesapeake, and Suffolk, and Isle of Wight County. Lemmings were present on 38 of 165 (23%) pitfall-trapping sites; their frequency was much greater in prime habitats dominated by grasses and sedges on damp organic soils. Thus, southern bog lemmings are distributed widely in southeastern Virginia and, where present, they often are among the most numerous species of small mammal.
Rose, Robert K.
"Distribution and Status of the Southern Bog Lemming, Synaptomys cooperi, in Southeastern Virginia,"
Virginia Journal of Science: Vol. 57
, Article 3.
Available at: https://digitalcommons.odu.edu/vjs/vol57/iss4/3