This report documents the findings of field investigations into the relative abundance and distribution of bats on the Kootenai National Forest and parts of the Lolo National Forest of western Montana from May 15 to September 28, 1993. Two primary methods of investigating species composition and abundance were used. Bat echolocation calls were monitored along selected transect routes beginning at sunset to record the relative abundance and activity patterns of bats. Mist nets were deployed across creeks, roads, trails, and adits to capture bats, providing the most reliable means for documenting species presence, and providing information on age, sex, and reproductive status. A total of 123 bats representing eight species were captured in the study area. Bats of the genus Myotis accounted for 91 percent of all captures. M. lucifugus was captured most frequently (48 percent), followed by M. californicus (15 percent), M. evotis (13 percent), M. volans (8 percent), Lasionycteris noctivagans (7 percent) and M. ciliolabrum (7 percent). One specimen each of Plecotus townsendii and Lasiurus cinereus were captured, comprising less than one percent of the total capture. Relative bat abundance varied greatly between 24 sites monitored during the study. High levels of bat activity were found at Camp 32 (74 passes/hr. ), Upper Fortine Creek (72 passes/hr. ), and Trout Creek (60 passes/hr. ). Sites demonstrating the most foraging activity as measured by feeding buzzed per hour were Camp 32 (n=29), Big Creek (n=14) and Bull Lake (n=13). The mean index of bat activity at the 24 transect locations was 33. 5 +/- 8. 9 passes per hour, and 6. 3 +/- 2. 7 feeding buzzes per hour (alpha=0. 025). Bats were regularly encountered foraging over road, creeks, and ponds in the study area. Of 1,031 bat passes detected at 24 transect locations, 19 percent (n=196) were attempting to capture prey. Foraging activity was highest at Camp 32 where 43 percent of bat passes contained a feeding buzz. Foraging bats were absent at three sites in the study area, but compromised at least 8 percent of all bat passes at every other site. Two adits investigated during this study are utilized by bats as night roosts. Myotis evotis were captured at the entrances of two adits on the Superior Ranger District. The Trout Creek adits, located on the west side of Trout Creek at approximately 3800 ft and 4100 ft elevation, were visited by male and female M. evotis on 13 July. The lower adit contained bat guano and culled moth wings. Only three juvenile bats (2 percent) were captured during the study: two male M. lucifugus at Lower Fortine Creek on 29 August, and one female M. volans at Rock Creek on 27 September. Females comprised 62 of 120 adults captured in mist nets (52 percent). Lactating M. lucifugus, M. californicus, M. ciliolabrum, and M. evotis were captured during the study between 15 July and 1 September. Lactating females represented 7 percent of the total bats captured and 13 percent of adult female bats captured. During the study, 24 percent of adult female bats captured were classified as either lactating (n=8), gravid (n=6), or postpartum (n=1). The observed low fecundity is likely due to the cold and wet weather experienced during the study. Information needs for the effective management of bat populations include knowledge of distribution, population status, and habitat requirements. Echolocation monitoring and mist-netting can provide much-needed information that is the first step towards protecting bat habitat.