METHODS AND MATERIALS 



Capture methods 



Mist nets were set across creeks, roads, trails, forest clearings, 

 and mine entrances. Nets of 6 m, 9 m, and 13 m length with black 

 or brown filament were deployed before sunset, and in most cases 

 left open until sunrise the following morning. Captured bats were 

 identified to species and sex. Forearm length was measured to the 

 nearest one-tenth mm with calipers. Body mass was determined by 

 weighing bats in a plastic bag of known mass with a calibrated 50- 

 gram Pesola scale. Bats were categorized as adult or juvenile by 

 examination of the degree of epiphyseal - diaphyseal fusion, and 

 tooth wear (Anthony 1988) . Bats were considered adult if 

 epiphyseal - diaphyseal fusion was complete. Reproductive 

 condition was assessed in female bats by palpation of the lower 

 abdomen to determine pregnancy (Racey 1988) and nipple morphology 

 and condition to identify lactating individuals. 



Echolocation survey methods 



Bat activity in the study area was monitored along selected 

 transect routes using a hand-held Skye monitor or QMC Mini Bat 

 Detector. Transects began shortly after sunset and continued, as 

 conditions allowed, for at least 30 minutes following the first 

 audible bat call of the evening. Echolocation calls were tuned to 

 the lowest detectable frequency, and categorized as bat passes or 

 feeding buzzes. The Skye monitor and the QMC Mini Bat Detector 

 are tunable monitors sensitive to echolocation calls produced by 

 bats common to Montana. The monitors function by generating an 

 audible signal that is characteristic of the received ultrasonic 

 signal. The Skye monitor and the QMC Mini permit easy 

 characterization of bat calls as passes or feeding buzzes, and can 

 be used to quantify general bat activity in a given habitat. 



Both monitors are sensitive to a small frequency range at any 

 given setting, preventing the operator from scanning all 

 frequencies at one time (Thomas and West 1984). This limitation 

 precludes identification of all bat calls to species within a 

 multi-species bat community. Identification of echolocation calls 

 to species is also complicated by the short duration of bat 

 passes, potential inaccuracy of the detector unit (Thomas and West 

 1984), and intraspecif ic variation in the minimum frequency of bat 

 calls (Thomas and others 1987) . The Skye monitor and the QMC Mini 

 are also of limited use in detecting P. townsendii due to the 

 relatively low intensity of their echolocation calls (van Zyll de 

 Jong 1985) . 



