ABSTRACT 



A program to close abandoned mines on BLM lands in southwestern Montana is 

 scheduled. Some of these mines may provide habitat for up to 15 species of bats, 

 including six U.S. Fish and Wildlife Service designated Species of Concern (former 

 category 2 species). The USGS Biological Resources Division provided funding to the 

 Montana Natural Heritage Program to survey abandoned mines in southwest Montana for 

 bat use. The objective of this study is to identify mines used by bats and evaluate a 

 variety of external and internal variables that would enhance predictive capabilities for 

 locating active roosts and hibemacula. The results of this study will assist in avoiding the 

 elimination of habitat that may be important to bats. 



Fieldwork was initiated on August 18, 1997 and continued through October 15, 

 1997. Eighty-six abandoned and inactive mines were visited. Sixty-eight mines had one 

 or more openings that might be suitable for bats. Openings had completely collapsed or 

 were backfilled at 1 8 mines. Eleven mines were rated as having high potential to provide 

 bat habitat. Mines which appeared to have the best potential for current bat use included 

 the Bluewing, Clipper, Hendricks, Huron/Cottontail, Keystone, Shoemaker, and an 

 unnamed cluster of shafts near the Watseca mine. These mines were extensive with 

 complex workings that may interconnect underground, facilitating air flow through the 

 mine. 



Mines in the Bannack mining district appeared to be the most stable and exhibit 

 the greatest potential for internal surveys. These mines were mostly located in limestone 

 substrate. Most mines in the Rochester mining district were situated in oxidized shists 

 that were very friable and appeared to be quite unstable and unsuitable for internal 

 surveys. 



External monitoring for bat activity was conducted at 66 openings from 34 mines. 

 Ultrasonic monitoring was conducted at 59 openings, while mist-netting was conducted 

 at eight locations. Bat activity was documented at 24 mines. However, analysis of 

 ultrasonic recordings is currently in progress, which may reveal more activity. Tentative 

 bat species detected by ultrasonic methods include unidentified Myotis species, western 

 long-footed myotis {Myotis evotis), silver-haired bat {Lasionycteris noctivagans), big 

 brown bat {Eptesicus fuscus), and possibly Townsend's big-eared bat {Corynorhinus 

 townsendii). Myotis ciliolabrum and M. evotis were the only species captiired in mist 

 nets, with 17 and three captures, respectively. Most captures were of adult non- 

 reproductive males, while only one adult non-reproductive female M. ciliolabrum and 

 one juvenile male M ciliolabrum were captured. 



Development of a GIS database of mine locations and sampled openings is in 

 progress. Field-survey data are being entered into appropriate data tables and linked to a 

 master database obtained from the Montana Bureau of Mines and Geology. 



