Northern Bog Lemming 



The northern bog lemming, a small, grayish brown, vole-like microtine, is related to the true 

 arctic lemmings {Lemmns). Nine poorly differentiated subspecies are currently recognized (Hall 

 1981). The northern bog lemming has a total length of 1 18-140 mm including its ver>' short tail 

 (19-27 mm) (Banfield 1974. Hall 1981). The combination of a tail less than 28 mm long and a 

 longitudinal groove in the upper incisors distinguish the northern bog lemming from all other 

 mice found in Montana. 



Little is known about northern bog lemming life history. Litter sizes vary from 3-8, with 2 

 (or more?) litters per year. It has been suggested that some animals breed the same year they are 

 bom (60-90 days old?). Such information is scattered throughout the literature. All literature 

 specific to northern bog lemmings deals mainly with distribution; other publications mention 

 lemmings only as a sidelight to the main publication. 



The northern bog lemming is boreal in distribution, occurring in North America from near 

 treeline in the north, south to Washington. Idaho, Montana. Minnesota, and New England. It 

 typically inhabits sphagnum bogs and fens, but is also occasionally found in other habitats 

 including mossy forests, wet sub-alpine meadows, and alpine tundra. One subspecies {S.b. 

 artemisiae) lives on sagebrush hillsides in eastern British Columbia (Anderson 1932). Southern 

 bog lemmings {S. cooperi) also inhabit a wide variety of habitats, all of which are marginal for 

 voles {Microtus spp.); bog lemmings may be competitively excluded from better quality habitats 

 by voles (Doutt at al. 1973, Linzey 1981). The northern bog lemming is rarely trapped and is 

 one of the least known mice in North America. It is listed as a Species of Special Concern by the 

 Idaho and Montana Natural Heritage Programs (Moseley and Groves 1990, Reichel 1997). 



A few relict populations occur in the lower 48 states; the subspecies chapmani occurs in 

 Montana. Idaho, and northeast Washington (Hall 1981). Bog lemmings are known from 4 

 locations in Idaho and 8 in Washington, all from within 80 km of the Canadian border (Johnson 

 and Cheney 1953. Wilson at al. 1980, Reichel 1984, Groves and Yensen 1989, D. Johnson pers. 

 comm.). The reasons for the disjunct nature of the populations may include: 1) the localized 

 nature of its primar>' habitat; and 2) the currently patchy distribution of a boreal species that was 

 more widely distributed during the Pleistocene (a glacial relict). 



Prior to 1992. evidence of bog lemmings in Montana included: 1) 6 locations on the west side 

 of Glacier National Park (Wright 1950, Weckwerth and Hawley 1962, Hoffinann at al. 1969, 

 Pearson 1991); 2) Shoofly Meadows in the Rattlesnake drainage north of Missoula (Adelman 

 1979), and 3) a single skull recovered from a Boreal Owl {Aegolius funereus) pellet west of 

 Wisdom (J. Jones pers. comm.); where the owl captured the lemming was unknown. In 1992 and 

 1993, 51 sites were trapped which located 10 new populations of northern bog lemmings 

 (Reichel and Beckstrom 1993, 1994). The Maybee Meadows site, just west of Wisdom, is the 

 southern-most known population of the species outside of New England and one of two Montana 

 populations known from east of the Continental Divide. The other eastern site is from near 

 Wood Lake, approximately 50 km south-south-west of the oil and gas leasing study area. All 10 

 sites found in 1992-1993 were associated with thick mats of moss. 



