Northern Bog Lemming 



I searched for suitable habitat for northern bog lemmings while traveling to and conducting 

 reptile and amphibian surveys across the study area (Appendix 3). The only site within the study 

 area with even marginally suitable habitat was Blackleaf Swamp. Northern bog lemmings were 

 not captured there, nor at nearby Pine Butte Swamp (Table 1 ). At each site however, 4-5 species 

 of other small mammals were captured (Table 2). These included masked shrews {Sorex 

 cinereus), montane shrews {Sorex monticolus), water shrews {Sorex palustris), meadow voles 

 {Microtus pennsylvanicus), and deer mice {Peromyscus maniculatus). Some shrews and 

 microtines will need the preliminary field identification verified when the skulls are cleaned. 



The northern bog lemming habitat on the study area is very limited; the only suitable site seen 

 was trapped. Trapping intensity was probably sufficient to detect lemmings had they been 

 present; more surveys are not warranted at this time. Additionally, many meadow voles were 

 captured at Blackleaf and bog lemmings have not been found at sites with high numbers of 

 meadow voles also present at any Montana location (Reichel and Beckstrom 1993, 1994). It 

 seems unlikely that bog lemmings were actually present at this site, but went undetected. 

 Trapping effort was 227 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 1993, 1994). At Pine Butte Swamp, however, the habitat suitable for 

 bog lemmings appeared to be of higher quality and to be more widespread than at Blackleaf 

 Given the lack of meadow voles and the large amount of habitat not trapped, it would be worth 

 doing additional bog lemming surveys at Pine Butte Swamp. If bog lemmings were located at 

 Pine Butte Swamp, then re-trapping Blackleaf Swamp should be considered. 



While northern bog lemmings were not found on the study area, it is near the edge of their 

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

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

 The Woods Creek site is only 50 km south of the study area and the habitat is seemingly both 

 lower quality and smaller than either Blackleaf or Pine Butte swamps. The Maybee Meadows 

 and the Wood Creek sites are the only known northern bog lemming sites east of the Continental 

 Divide in Montana. 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). 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 Little Belt Mountains. The known elevation range for 

 Montana is from 3340 ft (McDonald Creek, Pearson 1991) up to 6520 ft (Maybee Meadows, 

 Reichel and Beckstrom 1993). 



42 



