Survey of Shrews 1 1 1 



Ecologists studying small mammals often attempt to accurately depict 

 the structure of small mammal assemblages from trapping data. This effort is 

 complicated by differences in size and microhabitat use among species, which 

 can affect species- and trap type-specific probabilities of capture. Some types of 

 sampling, notably mark-and-recapture (Otis et al. 1978), may be used to estimate 

 capture probability and avoid this as a confounding factor. However, survey of 

 shrew (Soricidae) assemblages using live-trapping methods is made problematic 

 by high rates of trap mortality, and removal sampling is commonly employed 

 using pitfall traps (Kirkland and Sheppard 1994). Therefore, particular care must 

 be taken to minimize biases associated with sampling shrew communities. 



Many studies have examined differences among types of traps used to 

 sample shrews (e.g., Williams and Braun 1983). However, there is little infor- 

 mation regarding biases introduced through the arrangement of traps. Despite 

 recent efforts to promote standardized methods (Handley and Varn 1994, Kirk- 

 land and Sheppard 1994), many different pitfall-trap arrangements have been 

 used to survey shrews (Kalko and Handley 1993). Because trap arrangements, 

 like trap types, vary in their effectiveness at catching certain species (Bury and 

 Corn 1987, Mitchell et al. 1993), the assessment of shrew community structure 

 could be affected by trap arrangement. 



Pitfall trapping designs often take advantage of patterns of microhabitat 

 use, such as drifting behaviors often observed when small mammals encounter 

 an obstruction (Brillhart and Kaufman 1991). Because these behaviors may vary 

 among species, methods that rely on drifting could selectively under- or over- 

 represent certain species in samples. Two methods that take advantage of drift- 

 ing behavior are transects of traps placed along natural habitat structures, such as 

 fallen logs or exposed rock (selective transects), and drift-fence arrays, which 

 use artificial obstructions to direct small mammal movement. 



To assess how perception of a shrew assemblage might vary with trap- 

 ping design, we concurrently sampled shrews with selective transects, linear 

 transects, and drift-fence arrays in the southern Appalachians. To gain insight 

 into behaviors that might affect capture success with these trapping techniques, 

 we also examined microhabitat (coarse woody or rocky debris) use by shrews. 



METHODS 

 STUDY AREA 



We conducted our study at the Coweeta Hydrologic Laboratory 

 (35 o 03'N,83 o 25'W), located in the Nantahala Mountain Range of Macon Coun- 

 ty, North Carolina (Swank and Crossley 1988). Elevation at our study plots 

 ranged from 792 to 1,524 m above sea level. Study plots were restricted to plant 

 communities typical of cove hardwood and northern hardwood forests (Wharton 

 1977). Cove hardwood forests were characterized by the dominance of yellow 

 poplar (Liriodendron tulipifera), yellow buckeye (Aesculus octandra), black 



