Weckwerth and Hawley (1962) did not adequately describe the two specific sites where they 

 captured bog lemmings, but they were visited by D. E. Pearson (pers. comm.) who found they 

 were not located in fens or covered by thick moss mats. At these three sites trapping was 

 conducted multiple years, often twice each year (Camas Creek: 18 yrs [Hoffmann et al. 1969]; 

 Anaconda #1:6 yrs spring and fall [Jonkel 1959]; Anaconda #6: 4 yrs spring and fall [Jonkel 

 1959]). Despite this intensive trapping, only a total of 3 individuals have been taken in Camas 

 Creek in 2 of 1 8 years, and 1 individual at each of the two Anaconda Creek sites. A similar 

 situation exists with the McDonald Creek site which is in old-growth western hemlock {Tsuga 

 heterophylla) forest (Pearson 1991); this site has been trapped multiple times yielding only a 

 single lemming (June 1991 - September 1993, total 3600 trap-nights, D. E. Pearson, pers. 

 comm.). Apparent high quality habitat patches exist within 7 km of all four sites (Table 9, 10; 

 Pearson 1991; P. Lesica, pers. comm.). It seems likely that these sites are very marginal, and/or 

 that the individuals were found while dispersing from a nearby high quality site. 



Other habitat descriptions oiS. b. chapmani trapping sites in the northern Rocky Mountains 

 have sometimes included mention of sphagnum moss (Layser and Burke 1973, Groves and 

 Yensen 1989) while others have not (Wilson et al. 1980). I captured a single juvenile male 

 lemming on a dry alpine/subalpine ridge in northeast Washington (Wilson et al. 1980). 



Areas with extensive moss mats, particularly sphagnum, are the most likely sites in which to 

 find new bog lemming populations in Montana. Other habitats in Montana may either support 

 lower densities of bog lemmings; be used primarily by dispersing individuals; be used during 

 specific seasonal, climatic, or competitive situations; or be population sinks. Marginal habitats 

 and areas may be important to maintain population viability. The only certainty is that there is 

 much to be learned about habitat use by northern bog lemmings. 



Patch size of known bog lemming sites in Montana varies from 1-340 acres, with 7 of 13 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. 



