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, atypical 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. 



Probably all three alternatives have some element of reality. It seems likely that 1) some patch 

 complexes are isolated from others and have been for long periods of time; 2) some relatively 

 long distance movements may increase gene flow, supplement small populations, and allow for 

 recolonization of extirpated patches; and 3) while bog lemmings use a variety of habitats to a 

 limited (and largely unknown) extent, bog and fen habitats hold the densest populations of 

 lemmings. 



Research Methods. How do we get the information on distribution, habitat use, and movement 

 that we need to manage this species? Distributional information, and to a lesser extent habitat 

 use, has often been gathered using snap-traps. Detailed habitat use and movement data for small 

 mammals are most commonly obtained using mark-recapture techniques with live traps. 

 However, for northern bog lemmings, live traps are of very limited usefulness. This is because 

 Sherman live-trap use: 1) is labor intensive throughout the trapping period; 2) has very low 

 success with any bait tried; and 3) results in at least some mortality (4 of 6 known captures) 

 (Pearson 1991, Reichel and Beckstrom 1993). Pitfalls, used as live traps: 1) are labor intensive 

 especially during placement; 2) cannot be used in the saturated soil situations commonly 

 encountered in bog lemming habitat; and 3) result in at least some mortality during and between 

 trapping periods. Given these drawbacks, it seems doubtful that live-trapping methods, by 



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