Patch size of known bog lemming sites in Montana varies from 1 -340 acres, with 7 of 1 3 

 being less than 10 acres (Table 5). No patch sizes are known for 4 sites since they are not in 

 typical habitat (see preceding paragraph). Most sites found thus far in Montana appear to be 

 patches within potentially larger metapopulation patch complexes. These could include: a 

 Sunday Creek complex with a Bowen Creek complex; a Maybee Meadows complex possibly 

 with the Meadow Creek patch; and a McGee Meadows complex which may be part of a larger 

 complex in Glacier National Park. However, several small patches appear to be isolated. Numa 

 Ridge Bog (3 ac) is 5 km from the nearest fen/bog patch (Pearson 1991 ). Shoofly Meadows is 

 larger (24 ac) but may be 14 km from another suitable patch. Wood Creek is certainly at the 

 extreme, having only about 2 ac of moss mat habitat and being 13 km from the nearest known 

 potential site. While there appears to be substantial amounts of marginal habitat along Wood 

 Creek which might support bog lemmings, much of the riparian habitat has been heavily 

 impacted by domestic livestock grazing. 



This leads to questions about what constitutes a viable population of northern bog lemmings. 

 Three (somewhat) alternative hypotheses could apply: 1) lemmings live in habitat patches which 

 have been isolated for thousands of years; 2) lemmings move substantial distances between 

 patches supplementing (or recolonizing) the sub-population within a patch and contributing 

 genetic material; and 3) lemmings use habitats other than moss bogs/fens. 



Alternative 1 . Populations within patches such as Wood Lake and Numa Ridge Bog would 

 not appear to have been able to survive given the small habitat patch size, if they are indeed 

 totally isolated and if lemmings do not use habitats other than moss mats. This leads us to think 

 that this alternative is not completely feasible. 



Alternative 2. In several areas such as the Sunday Creek complex, the distribution and size of 

 known patches suggests movement between patches. The overall view that most patches in 

 Montana are relatively near other known, or potential, patches, gives support to this hypothesis. 

 Arctic lemmings are known to make spectacular movements during highs in the population 

 cycle; this could also be true of northern bog lemmings. Northern bog lemmings do undergo 

 populations fluctuations at least in central Canada (Edwards 1963). However, population cycles 

 in general appear to be less dramatic in: 1) more southerly areas, and 2) in areas with less 

 contiguous habitat for the cycling species. 



Alternative 3. Lemmings have certainly been found in habitats other than bogs/fens in 

 Montana and in other areas of their range. In the Montana sites where the habitat is atypical, 

 captures represent a rare event. Multiple trapping periods prior to and/or following the capture 

 have not resulted in regular additional captures of lemmings. In Glacier National Park, general 

 trapping for small mammals over nearly 100 years in numerous habitats has resulted in captures 

 of 5 lemmings at 4 sites (all atypical habitats) (Wright 1950, Hoffmann et al. 1969, Weckwerth 

 and Hawley 1962, Pearson 1991). In the rest of Montana, only 1 site has been found during 

 general small mammal trapping (Shoofly Meadows, a typical habitat site) (Adelman 1979). 

 However, when trapping focused on bog/fen habitat, 12 new sites were discovered in the past 4 

 years (Pearson 1991, Reichel and Beckstrom 1993, 1994). Many of these sites have had multiple 

 animals captured in a single night, supporting the premise that the fen\bog habitat is the primary 

 habitat for northern bog lemmings in Montana. The extent of lemming use of other habitats has 

 yet to be determined, but would appear to be low. 



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