I studied the efficacy of the Anabat I1 detector for obtaining reliable call structures for the identification of some southwestern bat species. A total of 20 locations in northern Arizona, southwestern Utah, and southern Nevada representing the available range in elevations and associated vegetation types, were sampled acoustically. The Anabat II in conjunction with a laptop computer provides an instantaneous output of echolocation call structure. Select sequences can be saved directly to the hard drive. Nineteen of the 22 species known to occur in the study region were identified by recognizable differences in the time/frequency characteristics of their echolocation calls. Species that forage in the open appear to use loud calls that can be detected at a greater distance than species that forage in clutter and use calls of low intensity. The present study suggests that the efficacy of bat inventories will increase with the establishment of better sampling procedures and the development of a comprehensive reference library of call structure incorporating the range of variation inherent within and between species.
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