SUMMARY 



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 echolcation calls were monitored along 

 selected transect routes begining 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%), 

 followed by M. californicus (15%), M. evotis (13%), M. volans 

 (8%) , Lasionyctereris noctivigans (7%) and M. ciliolahrum (7%) . 

 One specimen each of Plecotus townsendii and Lasiums cinereus 

 were captured, cortprising 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 Canp 

 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 buzzes 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 (a=0.025). 



Bats were regularly encountered foraging over roads, 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 bats passes contained a feeding buzz. Foraging bats were 

 absent at three sites in the study area, but comprised 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' and 

 4100' 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%) 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 conprised 



