INTRODUCTION 



The northern bog lemming {Synaptomys borealis), a small, grayish brown, vole-like microtine, 

 is related to the true arctic lemmings {Lemmus). Nine poorly differentiated subspecies are 

 currently recognized (Hall 1981). The northern bog lemming has a total length of 1 18-140 mm 

 including its very 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 on 

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

 lemmings only as a sidelight to the main publication (Appendix 1). 



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 (5. cooperi) also inhabit a wide variety of habitats, all of which are marginal for 

 Microtus; bog lemmings may be competitively excluded from better quality habitats by Microtus 

 (Doutt et 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 1995). 



A few relict populations occur in the lower 48 states; the subspecies chapman! 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 et 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 primary 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, Hoffmann et 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 

 V/isdom (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 (Figure 

 1) (Reichel and Beckstrom 1993, 1994). The Maybee Meadows site 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. All 10 sites found in 1992-1993 were associated with thick 

 mats of moss. 



