INTRODUCTION 



In 1996 the Mine Waste Cleanup Bureau of the Montana Department of Environmental 

 Quality installed culvert gate systems in the portals of four abandoned mine adits in western 

 Montana Two gates were installed at the McDonald ("Ravalli") Mine adits in Lake County, and 

 two more were placed in portals at the Gypsum Mine workings of Lewis and Clark Caverns State 

 Park in Jefferson County Inspection of these mine adits prior to gate installation revealed that 

 each was used at some time during the year by bats, particularly Townsend's Big-eared Bat 

 (Connor hi mis townsendii), a U.S. Fish and Wildlife Service species of special concern (Harvey 

 et al 1999) 



Gates were installed to allow for continued use of each mine working by bats while 

 prohibiting accidental livestock entry and unauthorized access by humans. Gates were built with 

 13 mm rebar attached to an angle iron gate frame, using recommended vetical spacing at least 

 5.75 inches and horizontal spacing at least 24 inches (Turtle and Taylor 1994, Dalton and Dalton 

 1995) The gate itself was attached to a corrugated metal pipe that was inserted into the mine 

 portal, surrounding the pipe with fill to assure that entry into the mine was through the pipe and 

 gate, the gate was secured with a protected padlock Although the gate design was supposed to 

 be bat-friendly, no follow-up study had been conducted at any of the sites to determine if bats 

 were still using the sites after gates were in place 



The objectives of the work described in this report were two-fold. First, determine the 

 effectiveness of the gate design in its primary function of allowing continued access by bats to 

 the mine workings Second, gather mine environment data (temperature, relative humidity) 

 continuously over a several month period to aid in characterization of the mine environments 

 where bats occurred 



STUDY SITES AND METHODS 



The McDonald ("Ravalli") Mine is just west of the small community of Ravalli, in Lake 

 County. T18NR20WS3 1NWNE at about 853 m (2800 ft) elevation near the Jocko River and at 

 the southern boundary of the National Bison Range The mine includes three open adits that 

 produced crude copper ore, the lower two of which are now gated The mine has not been 

 worked since 1917 (Rossillon 1995) 



The Gypsum Mine lies within the boundary of Lewis and Clark Caverns State Park, in 

 Jefferson County, about 275-305 m (900-1000 ft) elevation below the mouth of the cave, and 

 overlooking the Jefferson River The mine is part of a 1 18-acre claim patented in 1915 that 

 includes a number of prospects, a large open pit, and a couple of adits The two gated adits are 

 in T1NR2W in S21NWNW (adit #1) and S20NENE (adit #2), at about 1432 m (4700 ft) and 

 1390 m (4560 ft) elevation, respectively 



During mine surveys, all bats encountered were recorded and identified to species, if 

 possible, taking care not to disturb the bats Location of bats within the mine was noted, and a 

 series of temperature and relative humidity measurements were made with a Bacharach sling 

 psychrometer Mines were explored to the fullest extent possible, which depended in part on 

 underground configuration and relative hazard At least one electronic data logger (HOBO, 

 Onset Computer Corporation, Bourne. MA) was installed in each working, usually within the 

 area occupied by bats Data loggers, set to record temperature and relative humidity every 6 



