Bat use of mines. We observed four species of 

 bats at the ten mines (Table 3). Corynorhinus 

 townsendii was present at six mines, Myotis 

 ciliolabrum at five mines, and M evotis and 

 Eptesicus fuscus at one mine each. In all cases, 

 we observed only small numbers of individuals. 



Three of the mines (McDonald Adit # 1 , Gypsum 

 Adits #1 and #2) were hibemacula for C. 

 townsendii, with number of hibemating individuals 

 ranging from 1-8. All C. townsendii inthe 

 McDonald Adit # 1 were roosting singly on the 

 walls < 1 .0 m above the floor within 40 m of the 

 portal, hi the Gypsum Adit #1 a single C. 

 townsendii was on the wall <1 .0 m above the 

 floor and 13.8m from the portal. In the Gypsum 

 Adit #2 we found torpid bats ( 1 unidentified 

 Myotis and 7 C. townsendii) between 6.0-25.5 

 m fi-om the portal; all bats were < 1 .0 m above the 

 floor and roosting singly. In the only other mine 

 entered during winter (Hendricks) we found single 

 M. ciliolabrum and E. fuscus, both about 1 .5 m 

 above the floor 143 m fi-om the portal. A mater- 

 nity roost of 25 C. townsendii in the McDonald 

 Adit #2 was the largest number of bats we found 



in a single mine; these were in a tight cluster on the 

 wall near the ceiling about 1 .5 m above the floor 

 and 1 4 m from the portal. We found no other 

 maternity roosts. 



The remaining bats we observed or captured 

 (Table 3) appeared to be using the mines as day 

 or night roosts. The single M. ciliolabrum we 

 found in June in the Hendricks Mine was a female 

 fially exposed on the wall near the ceiling about 1 .5 

 m above the ground. Three of five M 

 ciliolabrum we captured at the portal of the 

 Unnamed Adit #1 on 11 June were non-lactating 

 females (teats visible, however). The two M. 

 evotis we captured in August at the Unnamed Adit 

 #2 were lactating females, the only reproductive 

 female bats we captured. All tlie other individuals 

 that we handled were males. 



We were unable to fiiUy survey the three largest 

 mines, McDonald Adit # 1 , Hendricks Mine, 

 Union Mine, although we investigated 60-70% of 

 the workings in each. Therefore, it is possible, 

 even probable, that we missed seeing some bats 

 during summer in the McDonald Adit # 1 , and in 



Table 3. Bats observed during 1998-1999 at abandoned mines in southwestern Montana. 

 An asterisk following a mine name indicates bats were captured at the mine portal. 



^ Townsend's Big-eared Bat 

 Myotis ciliolabrum. Western 

 fuscus. 



Corynorhinus townsendii. Western Small-footed Myotis 

 Long-eared Myotis Myotis evotis. Big Brown Bat Eptesicus 



