METHODS 



Historical records of bats from northwestern Montana and adjacent areas of Idaho and Canada 

 were obtained from the literature (see Bibliography). These records provide data on breeding 

 status, habitat use, seasonality of occurrence, and distribution. Museum records, other than those 

 previously published, are not included here. 



Field work in 1 994 was conducted from late July to mid-September. An attempt was made to 

 visit the six Districts of the Kootenai National Forest (Cabinet, Fisher River, Fortine. Libby. 

 Rexford. and Tliree Rivers). Survey sites were chosen based on accessibility and the presence of 

 water nearby, as bats tend to concentrate their foraging activity over water sources where insects 

 are abundant (all bats in this region are insectivorous). However, forest clearings or narrow 

 corridors within forest stands were also monitored. Habitat data were collected for each site (see 

 field form in Appendix 1 ), and an attempt was made to sample different cover types. Samples 

 from different habitats are too few for statistical analyses, however, and are not presented here. 

 No potential roost sites (caves, mines, cavities in trees) were visited or checked, despite the 

 presence of several in the region. 



Ultrasound bat detectors were used during the 1 994 bat survey on the Kootenai National 

 Forest. Thomas and West (1989) provide a general discussion of sampling methods for bats. 

 Each method has strengths and weaknesses for survey work, with no single method being 

 definitive. Mist-netting, another commonly employed technique used in 1993 (Roemer 1994), 

 has the advantage of allowing in-hand identification of individuals and collection of data on sex 

 and reproductive condition, neither of which are obtainable with bat detectors. Some bats may 

 escape capture in nets, however, and some species present at a particular site may go undetected. 

 Detectors can deteniiine the presence of species that may be missed during mist-netting, but they 

 are not without drawbacks. Call duration, time between calls, call structure, and call frequency 

 can vary significantly with habitat and between individuals (Erickson 1993). often making 

 species identification difficult. On the Kootenai National Forest. Kdyotis evotis was the only 

 species oiMyotis which could be accurately distinguished from other members of the genus 

 using a bat detector. Ideally, a combination of mist-nets and bat detectors would be employed at 

 a given site in order to obtain the most accurate picture of distribution; mist-netting is 

 time-consuming, however, and therefore permits fewer sites to be surveyed within the allotted 

 fime period. 



Microchiropteran bats use a variety of ultrasonic vocalizations as echolocation aids for 

 navigation and prey capture. Fortuitously, a number of studies have determined that the signals 

 emitted by many species of bats can be used to distinguish among species (e.g., Barclay 1986, 

 Fenton and Bell 1981. Fenton <?/ o/. 1983. MacDonald e/ a/. 1994). This characteristic permits 

 the assessment of species-presence during inventory work through use of portable ultrasound bat 

 detectors. ANABAT II bat detectors (Titley Electronics, Ballina, Australia) were used during 

 the 1 994 field season. These detectors are sensitive to broadband ultrasonic calls common in bat 

 vocalizations (usually 20-180 kHz) . Ultrasonic signals in the range of bat vocalizafions are 

 captured, converted to an audible frequency (up to 10 kHz), and recorded on magnetic tape. 

 Detector units (consisting of the detector, timer/tape-driver, and a voice-activated cassette tape 

 recorder) were set up before dusk near bodies of water and forest openings (where bat activity 



