DISCUSSI(>I 



Survey methods 



A study designed to determirie absolute and quantitative abundance of 

 a species is a census. Several methods, such as mark-recapture and 

 visual counts (Thanas and LaVal 1988), have been used by researchers 

 to estimate absolute bat numbers, but these have generally been in 

 enclosed areas such as caves, or at specific roosting or maternity 

 sites. Determining quantitative measures of bat densities in a given 

 habitat or foraging within a given area is not ocffisidered possible 

 with current technology (Findley 1993, Thomas and West 1989). 



A survey is designed to provide relative and qualitative information, 

 in short to "respcxi(d) to such questions as. Does habitat A have more 

 bats of a given species than habitat B does? or Is species X more 

 abundant before or after modification of habitat Y?" (Thomas and West 

 1989). Findley (1993) concluded that the best that can be done by a 

 comnunity ecolcgist studying bats is to assess the relative abundance 

 of different species and to corpare regions and habitats with respect 

 to the numbers of bats obtained for given amounts of effort applied. 



Summer roost counts, visvial counts of foraging bats, ultrasonic 

 detectors, vampire bites, and mist-netting and trapping were methods 

 listed by Thomas and LaVal (1988) to estimate bat abundance in 

 habitats or other geographic areas. The use of ultrasonic detectors 



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