116 Timothy S. McCay, Joshua Laerm, M. Alex Menzel 



and William M. Ford 



spp. and B. brevicauda captures between transects and arrays. Likewise, this 

 table supported dependence (G 2 = 8.718; P = 0.003; df = 1). The odds ratio for 

 this table was less than unity (0 = 0.168; Z = -2.375; df = 242), indicating that 

 Sorex spp. were more likely than B. brevicauda to be captured using arrays. 



MICROHABITAT USE 



None of the shrews examined showed strong relationships with the 

 abundance of rocks, logs, and stumps within 2.5 m of the trap stations. There is 

 some evidence that Sorex fumeus selectively used habitat structure, as the cap- 

 ture success of this species was significantly correlated with the abundance of 

 rocks (r 2 = 0.017; P = 0.050) and logs (r 2 = 0.018; P = 0.047). Sorex cinereus 

 was correlated only with the abundance of rocks (r 2 = 0.026; P = 0.016). Final- 

 ly, B. brevicauda was not correlated with any of the habitat features examined. 

 It should be noted that the correlations presented above are, while statistically 

 significant, exceedingly weak. For example, the abundance of rocks accounts for 

 only 1.7% of the variability in S. fumeus capture. 



In agreement with our microhabitat correlations, capture success of S. 

 fumeus showed a highly significant, although weak, relationship with proximity 

 to structure (r 2 = 0.034; P = 0.006; df = 218). Sorex cinereus capture success was 

 not significantly related to proximity to structure (r = 0.009; P = 0.158; df = 

 218), nor was the capture success of B. brevicauda (r 2 = 0.002; P = 0.481; df = 

 218). 



Thus, S. fumeus showed the strongest relationship with habitat structure 

 and the greatest positive differences between selective transects and linear tran- 

 sects in 1994 (220%) and 1995 (180%; Tables 1 and 2). Captures of S. cinereus 

 were less strongly related to habitat structure and showed smaller, positive dif- 

 ferences between selective and linear transects in 1994 (170%) and 1995 (160%). 

 Blarina brevicauda was not correlated with the abundance of any structural habi- 

 tat features or proximity to structure and was the only species to exhibit a nega- 

 tive difference between selective and linear transects (-20% in 1995), reflecting 

 a higher capture success at traps placed without regard to microhabitat features 

 than those traps placed selectively. 



DISCUSSION 



The relative capture frequencies of Sorex fumeus and S. cinereus, when 

 considered with respect to each other, were not significantly affected by trap 

 arrangement. This suggests that any of the three methods considered would pro- 

 vide a similar depiction of the relative abundance of these species in similar habi- 

 tats. Furthermore, the capture rates of these species using transects were similar 

 over a two-year period. Thus, our data for S. fumeus and S. cinereus suggest that 

 in comparisons over time, selective and linear transects provide estimates of rel- 



