DISCUSSION 



Most of the mine workings examined during this survey in the Philipsburg area had low 

 potential for significant use by bats At best, the majority of accessible workings might be used 

 as night roosts by one or a few individuals, sites where bats rest and digest food following 

 emergence and foraging. Nevertheless, few workings offered any evidence of use, recent or 

 otherwise, by bats. 



The Russian Gulch Mine, because of the extent of workings and movement of air through 

 the mine, has the greatest potential for use by bats but there is no evidence that it is currently 

 used by them. Lack of use may be related to the size of the portal openings, but bats are known 

 to use sites with openings this size or smaller (personal observation) In its present state this 

 mine is most suitable as a hibernaculum, because it is relatively cold and humid, factors not 

 favored by female bats for raising young (see Humphrey and Kunz 1976, Betts 1997). 



Other workings most likely to be used by bats include the Frost Creek adit #4 (old 

 droppings present, but no activity detected during overnight monitoring), and the Cliff Creek adit 

 #6 (obstructed with cable netting and no droppings present, but might be used if the netting was 

 removed) Both workings are simple and relatively shallow (22-27 m in extent), and would be 

 used by only a few bats at a time The Frost Creek adit #4 is most likely to be used as a night 

 roost because of its N-facing aspect and cooler, more humid mine climate. The Cliff Creek adit 

 #6, on the other hand, has a S-facing aspect, and is warmer and less humid than the Frost Creek 

 working. This site has potential for use as a maternity roost by a few individuals or as a night 

 roost (see Hendricks 1999). Both sites have the potential for use as hibernacula, but more 

 detailed climate data are needed to support this contention 



Few bats were observed during the mine survey, and those seen (in flight) were not 

 identified to species, although at least two species were observed (based on size differences and 

 vocalizations) Several species of bats could occupy the survey area, including several species 

 that use caves and mines Western Long-eared Myotis (Myotis evotis), Little Brown Myotis (M. 

 luafugus), and Long-legged Myotis (A/, volans), all mine-dwelling species, have been collected 

 from Granite County (Table 1 ) Other species reported from Granite County, based mostly on 



Table 1. Bat specimens collected from Granite County, Montana 



' UMZ (University of Montana Zoological Museum). CMNH (Carnegie Museum of Natural History). 



