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 

 captxired while foraging. Most bats captured are probably "oonmuting" 

 along habitually used pathways on the way to or from foraging or 

 watering areas (Thotnas and West 1989). There is therefore an 

 inherent site bias that cannot provide unequd. vocal information on the 

 distribution of bats among sites or habitats using mist-nets as a 

 survey method (Thctnas and West 1989). Mist nets were used in this 

 study to document species occurrence, vrfiile realizing that there are 

 inherent biases in the method that select against the documentation 

 of some species. 



A potential problem with capture methods such as mist-netting is mis- 

 identification of bat species. Most species in Montana can be 

 identified easily using one of several available dichotcmous keys, 

 such as Van Zyll de Jong (1985). When there was any question of 

 identification during this study, the bat in question was collected 

 and taken to an expert for positive identification. Bats most easily 



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