DISCUSSION 



Distribution . While northern bog lemmings were not found on the BLM-GRA, it is within their 

 range in Montana which includes from the northwest comer of the state east to the Rocky 

 Mountain Front, and south tlirough the mountains to Lost Trail Pass on the Continental Divide 

 (Figure 1). The Maybee Meadows site is the southern-most site known for the species outside of 

 New England; two sites in New Hampshire are about 160 km farther south (Clough and Albright 

 1987; Reichel and Beckstrom 1993, 1994). The Maybee Meadows and the Wood Creek sites are 

 the only known northern bog lemming sites east of the Continental Divide in Montana. We 

 expect additional populations to be found across western Montana, perhaps as far south as 

 Yellowstone National Park, and possibly east to mountain ranges such as the Belt or Snowy 

 ranges. The known elevation range for Montana is from 3340 ft (McDonald Creek, Pearson 

 1991) up to 6520 ft (Maybee Meadows, Reichel and Beckstrom 1993). 



Detectability . The habitat in the BLM-GRA appears to be very limited for northern bog 

 lemmings. The best 4 of the 12 sites seen were trapped; trapping intensity was probably 

 sufficient to detect lemmings had they been present. Unless areas with larger moss mats are 

 found on the BLM-GRA more sur\'eys are not warranted at this time. Trapping effort at each site 

 ranged fi-om 204 to 230 trap-nights over 2 nights. Previous snap-trap effort required to document 

 bog lemming presence (at sites found to contain the species) averaged 1 14 trap-nights, and 

 ranged from 46 trap-nights (during 1 night) to 224 trap-nights (during 3 nights of trapping) 

 (Reichel and Beckstrom 1992, 1993). 



During 1992-1993 lemmings were found at 10 of 17 sites that appeared to have suitable 

 lemming habitat. Either the lemmings are at those sites and we failed to detect them, or we 

 sampled some sites with apparently good habitat, which actually lacked lenunings. Probably a 

 combination of the two is actually the case (Reichel and Beckstrom 1993, 1994). The percentage 

 of sites with good habitat which had lemming captures was slightly higher than that of Pearson 

 (1991) who found lemmings at 3 of 11 bog/fen sites trapped with Sherman live traps in 1989-90. 



Habitat Patches . Bog lemmings have been found in at least nine community types (Table 4), 

 including some of those present at the four sites trapped on the BLM-GRA in 1995. However, 

 peatland communities constitute a very small proportion of the landscape in Montana and have 

 not been adequately classified (Bursik and Moseley 1 992). Whether new information on these 

 fens will result in newly defined community types which closely approximate habitat used by 

 northern bog lemmings remains to be seen. Extensive thick moss mats were present in all but 

 one of the lemming sites found during our previous surveys (Reichel and Beckstrom 1993, 

 1994), and were also present at Numa Ridge Bog, McGee Meadows (Pearson 1991, P. Lesica 

 pers. comm.) and Shoofly Meadows (Pearson 1991, S. Chadde pers. comm.). 



In 1993 I spent several hours along Camas Creek in the vicinity of the first lemming 

 population known from the state (Wright 1950) and found only scattered clumps of moss. 



