TABLE 2. Standard skull measurements from shrews {Sorex) collected in the Centennial 

 Sandhills, Beaverhead County, Montana in 1999. All measurements (in mm) were made with 

 a microscope fitted with an optical micrometer. Sample size varies where skulls are Incomplete. 



The majority of shrews — 72% ( 1 8 of 25 cap- 

 tured) — were trapped in the East Hills. Equal 

 numbers of shrews were captured on pitfall 

 transects in the West and East Hills (7 individuals 

 each), even though there were twice as many trap 

 nights of effort in the West Hills (4680 vs. 2320). 

 This suggests that shrews are much more abundant 

 in the southern areas of the East Hills. This pattem 

 also holds for the drift array results (Appendix 6). 

 The 2 confirmed Preble's Shrews came from 

 pitfall line 3, and the 3 potential Preble's speci- 

 mens from drift array 3 in the East Hills and pitfall 

 line 4 in the West Hills. These results suggest that 

 this rare shrew may be widespread at low density 

 in the Sandhills. 



There was no clear correlation between pitfall trap 

 captures and habitat types. More shrews were 

 captured on lines with moderately dense shrub 

 cover than where shrub cover was sparse (see 

 Appendix 3). The difference, however, was not 

 statistically significant (binomial probability P= 

 0.338), partly because of small sample size. 

 Complicating the situation were the drift array 

 results: no shrews were captured in array 1 (a 

 blowout with sparse cover) but 6 were captured in 

 array 3 (also a blowout with sparse cover), and 5 

 in array 2 (low depression with sparse cover). 



Five of 6 Masked Shrews (5. cinereus) were 

 caught in sparse shrub/grass cover, but total 

 captures were too few to identify with confidence 



any microhabitat association. The 2 confirmed 

 and 2 of the potential Preble's Shrews were also 

 captured in sparse shrub/grass cover Dusky 

 Shrew (S. monticolus) captures were evenly 

 divided between habitats with moderate and 

 sparse cover The lack of obvious microhabitat 

 association, especially for Masked Shrew, has 

 been noted at other sandhills and shrub-steppe 

 locations (Wrigley 1974, Kirklandetal. 1997). In 

 other areas, each species has been found in shrub- 

 steppe habitats (Ports and George 1990, Kirkland 

 etal. 1997, Sutter etal. 1999), sometimes occur- 

 ring together in the same habitats as they do in the 

 Sandhills. However, Dusky and Masked shrews 

 are often considered montane species associated 

 with mesic habitats. 



Lagomorphs : We encountered 2 Lagomorph 

 species during our surveys. White-tailed Jackrab- 

 bit {Lepus townsendii) was seen only once, on 2 1 

 September in the West Hills, but fresh remains 

 were also foimd in the West Hills on 25 May and 

 in the East Hills on 30 July, indicating a wide- 

 spread distribution but at relatively low density. 

 Jackrabbits are apparently less common now in 

 the Centennial Valley than they were 10-15 years 

 ago (D. Gomez, personal communication). Black- 

 tailed Jackrabbit was seen once, on 27 July west 

 of Tepee Creek in sparse low-stature sagebrush 

 (T13S,R1W,S19SW). This species has not yet 

 been reported on Refuge lands, but could occur in 

 the Sandhills portion of the Refuge. Davis ( 1 937) 



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