The uranium mines that were entered varied considerably in depth 

 from approximately 50 m to more than 300 m (the long tunnels were 

 not explored beyond this depth) . Temperatures ranged between 

 4.4° C and 9° C. Humidity was not recorded, but all of the 

 tunnels, especially the deeper shafts, were very damp and 

 probably had humidities approaching 100%. Few crevices and 

 cracks were apparent in these shafts, likely making them 

 unsuitable for most species of bats. However the tunnels were 

 similar in structure to tunnels where the Townsend's big-eared 

 bat has been found (per. obs.). One adult male Townsend's big- 

 eared bat was found roosting in one of the shallow (100 m) 

 tunnels. This individual represented the only sign of bats found 

 in these mines. 



Additionally, one adult male Townsend's big-eared bat was located 

 roosting in an abandoned building on private land just west of 

 Horseshoe Bend Campground. 



TABLE 3. — All Bat Captures, 1990 



Total 930 171 1,101 



Trapping success was generally greater at the caves, where 960 

 (87%) bats were captured in 30 nights of trapping. Considerably 

 fewer bats were captured at water sources: 143 (27%) on 20 

 nights of trapping. However, species diversity tended to be 

 greater at the water sources, and neither the pallid bat, 

 spotted bat, silver-haired bat, nor the hoary bat occurred at the 

 caves. Conversely, only one species, the Townsend's big-eared 

 bat, occurred at the caves but was not observed at the water 

 sources. Three species of the genus Myotis were most abundant at 

 the caves, but relative proportions of these species varied 

 between caves, and Plecotus townsendii and Eptesicus fuscus did 

 not occur at all caves. At both Mystery Cave and Little Ice 

 Cave, where the most bats were captured (892, 81%), as well as 

 Syke's Cave, only species of the genus Myotis were captured (with 

 the exception of one Plecotus townsendii captured at Mystery 

 Cave) . 



11 



