Adit 106 7 m from the portal Maximum temperatures were recorded during the first two weeks 

 of July in each adit, minimum temperatures were recorded on 21-22 December 1998 (see Figures 

 1. 3, 5) The pattern of variation in relative humidity among adits was identical to the pattern for 

 temperature Relative humidity varied by 81 9% at the shallow location in the East Adit (Figure 

 2). but only by 10 .5° o at the deep location (Figure 4, Table 1 ) In the West Adit, relative 

 humidity varied by 38.8% during the sample period (Figure 6) Maximum values occurred on a 

 range of dates in each adit, from 29 January until July deep in the West Adit and between 5 May 

 and July shallow in the same adit, to a shorter period ( 1 8 June to 6 July) in the West adit 

 Minimum relative humidity was recorded on 21 December in the East Adit, but on 13 July in the 

 West Adit 



Gypsum Mine Sites. The two gated Gypsum Mine adits (#1 "upper" and #2 "lower") were 

 surveyed completely on 6 January 1999, when a single data logger was installed in each The 

 upper Adit #1 extends straight back for 22 4 m (73.5 ft) from the portal, the lower Adit #2 

 extends straight back for 44 m ( 144 4 ft) In Adit #1, one Townsend's Big-eared Bat was 

 hibernating 1 m (3.3 ft) above the floor 5 8 m (19 ft) from the drift face. In Adit #2, one 

 unidentified Myotis (probably the Little Brown Bat A/, lucifugus) was found hibernating wedged 

 in a crack about 5 m (16.5 ft) from the portal, four Townsend's Big-eared Bats were 

 hibernating between 3 4 and 8.0 m (1 1.2 and 26 2 ft) from the portal Three additional 

 Townsend's Big-eared Bats were hibernating about 25 5 m (83 7 ft) from the portal No bats 

 were observed in either adit when data loggers were retrieved on 13 July 1999 



In Adit n\ a data logger was installed where the lone bat was hibernating 5 8m from the 

 drift face Unfortunately, this data logger failed to record any data during the recording period (7 

 January to 13 July 1999) However, at the time the data logger was installed, temperature in this 

 adit ranged from 3.9-6 4°C (39-43 5°F), the warmest value about 3 m (9 8 ft) from the drift face, 

 relative humidity was 53% 1 2 6 m (4 1 3 ft) from the portal to the drift face In Adit #2 a data 

 logger was installed 8 m (26.2 ft) from the portal (36 m from the drift face), at the far end of the 

 primary zone of bat occupancy At this location mine temperature varied by 6 8°C (12 2°F) in 6 

 months, relative humidity varied by 27 8% (Table 1 ) Maximum temperature and relative 

 humidity (Table 1 , Figure 7 and 8, respectively) were recorded in the first part of July, just prior 

 to data logger retrieval, minimum values for each variable were recorded on 24 January 



DISCUSSION 



Workings at both mine sites were gated because they were known to harbor bats in 

 winter Townsend's Big-eared Bat (( 'orynorhmus townsendii) has been known to occupy the 

 McDonald Mine workings since at least 1965 (specimens UMZ9942 through UMZ9945, 

 collected 5-6 December, P L Wright Vertebrate Museum, University of Montana) More 

 recently the three adits of this mine were surveyed on 6 November 1996 Five hibernating 

 Townsend's Big-eared bats were present in the East Adit (20-61 m from the portal) and another 

 was activelv thing, no bats were present in the West Adit One fresh dead big-eared bat was 

 found in the upper adit as was one active individual, probably the same active bat in the East 

 Adit Use of the Gypsum Mine adits is less well-documented, but bat activity in and around 

 Lewis and Clark Caverns has been reported for many decades (Lee Flath, pers comm ) 



The surveys reported here indicate continued use of all gated mine workings by bats, 

 certainly an encouraging finding that indicates the gate design in use is. indeed, bat friendly 



