were largely impractical for logistical and monetary reasons), and localized availability of 

 surface water with inadequate knowledge of how bats use the landscape around roosts. Also, the 

 importance for bats of mines on private lands in the study area is unknown, and long-term 

 security of these for use as bat roosts is also open to question. 



Mines with obstructions are, on average, less attractive to bats for roosts, but some of 

 these were used nevertheless Removal of obstructions should be considered as an option for 

 making mine workings more attractive to bats, especially at some mines where grated shafts 

 predominate (the Emma is an example) Mine workings where bat activity was confirmed 

 should be gated or protected by means other than closure. This assumes that policy dictates they 

 are to be made accessible to bats but not to humans and/or livestock, and that adequate funding 

 exists or can be allocated for such management activity. With limited funding, highest priority 

 for protection should be given to those workings with the greatest amount of documented 

 activity, and sites where Townsend's Big-eared Bat (a BLM Special Status species in Montana) 

 was identified. 



Mine closure methods 



Bat friendly gates (see Turtle and Taylor 1994, Dalton and Dalton 1995) should be 

 installed on adit portals not already protected Gates should be constructed such that they do not 

 restrict air movement or passage of bats, yet prohibit livestock and unauthorized human entry A 

 bat-friendly gate design has been installed by the Mine Waste Cleanup Bureau, Montana 

 Department of Environmental Quality at four abandoned mine adits elsewhere in Montana that 

 are known to be used as hibernacula and/or maternity roosts by Townsend's Big-eared Bat 

 {Corynorhmus townsendn) These adits were still in use in 1999 by this species and at least one 

 species of Myotis three years after gate installation The design uses 13 mm rebar with 

 recommended spacing (5.75 inch vertical, 24 inch horizontal) on a swinging gate, secured by a 

 protected lock (not an exposed chain and/or lock) and secured to the end of a corrugated metal 

 pipe that is inserted into the mine portal. The corrugated pipe is then covered with fill to assure 

 that entry is through the pipe and gate Cable netting (usually about 8x8 inches mesh size) has 

 been used with success in a few situations, but is more easily breached by humans than are 

 properly designed gates Cable netting is suitable primarily to maintain mine airflow while 

 hindering access by humans and livestock, and is not recommended for protecting portals used 

 by bats 



The current gate design used on many shafts in the study area, where a fine-mesh grate 

 (mesh size of 1 x 3 inches) is placed at ground level over the portal, effectively prevents their use 

 by bats Many grated shafts have the potential to be used by bats if they were made more bat- 

 friendly Current grates can be replaced with grates built with angle iron having the proper 

 spacing (5.75 x 24 inches) that will allow passage of bats (Dalton and Dalton 1995) However, 

 use of this design without fencing may fail to prevent livestock from stumbling onto these and 

 being injured Replacement of the current grate design with a box-type or "cupola" design (eg. 

 Turtle and Taylor 1994) on shafts currently protected should be considered Fencing around 

 shafts, the least obtrusive method to bats for preventing injury to livestock, fails to address the 

 potential hazard for humans 



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