apparently restricted in Montana to the vicinity of the Pryor 

 Mountains south of Billings (Worthington and Ross 1990). Most of 

 the species known to inhabit the state, however, could 

 potentially be found on the Forest. Documentation of both 

 general species diversity, as well as the occurrence of species 

 suspected of being relatively unconunon, such as Townsend ' s big- 

 eared bat {Plecotus townsendil) , is necessary for Forest planning 

 and management, considering the mandates of federal legislation 

 to manage for species diversity, and to maintain viable 

 populations. 



Though an experienced observer can identify many bat species 

 visually by size, shape, and flight characteristics, when light 

 conditions allow, documentation was not considered positive for 

 this study unless specimens were captured. 



Capturing bats with mist nets incorporates several biases. In 

 this study, nets were never more than 15 feet above the ground, 

 and therefore selected against the capture of high flying 

 foragers. Other bats, such as the Townsend ' s big-eared bat are 

 slow, maneuverable flyers that can usually detect and avoid a 

 mist net or a harp trap, and thus are difficult to document by 

 capture with these techniques. All insectivorous bats are 

 probably capable of detecting and avoiding mist nets using echo- 

 location. Few bats are thus captured while foraging. Most bats 

 captured are probably "commuting" along habitually used pathways 



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