INTRODUCTION 



Azure Cave (Figure 1), located in the Little Rocky Mountains of Phillips County in north- 

 central Montana, was recognized as a significant natural underground feature almost from the 

 date of its discovery in the late 1950 ? s (Howard and Hintzman 1964, Chester et al. 1979). 

 Although not large (total mapped passage is about 580 m, or 1900 ft), the cave is one of the 

 deepest (about 67 m, or 220 ft) in Montana. The cave also harbors some of the finest cave 

 formations in the state, quickly prompting efforts to protect the cave from vandalism. At the 

 same time, the cave was considered for development as a tourist attraction. Although a gate was 

 installed in 1961 (Howard and Hintzman 1964), vandalism and unauthorized entry continued for 

 several years until the gate was modified to make entry more difficult. Following modification of 

 the gate, several authorized entries have occurred, but unauthorized entries still continue, albeit 

 with less frequency than before. Records of the timing and frequency of authorized entries into 

 the cave have not been kept until recently. Current policy is to admit entry only under special 

 circumstances, and internal visits are restricted to inventory and monitoring of cave features. 



Early cave inventory and mapping studies mentioned that Azure Cave was used by a large 

 number of bats (Howard and Hintzman 1964, Campbell 1978), but no count was available and 

 the species using the cave remained unverified. A complete cave inventory conducted in 1978 by 

 Chester et al. (1979) not only provided a complete count of bats hibernating in Azure Cave, but 

 also documented seasonal use of the cave by bats, data that have significant management, as well 

 as biological, implications. Bats continue to be the focus of concern nation-wide, because of 

 their vulnerability to disturbance and the loss of many of their traditional roosts, such as caves 

 and abandoned mines (Humphrey 1978, Turtle 1979, LaVal and LaVal 1980, Gates et al. 1984, 

 Richter et al. 1 993). Several species potentially found in the Little Rocky Mountains were on the 

 former Candidate (C2) list maintained by the U.S. Fish and Wildlife Service, and Townsend"s 

 Big-eared Bat (Corynorhinus townsendii) is currently listed as a BLM Special Status species, and 

 a U.S. Forest Service Sensitive species, in Montana. Recent proposals to expand mining 

 operations in the Little Rocky Mountains near Azure Cave stimulated agency biologists to fund 

 an inventory of the bat fauna in the area of proposed mine expansion, which included Azure 

 Cave. The inventory would provide current baseline data regarding the importance to bats of 

 various landscape features, such as water sources, abandoned mines, as well as caves, from 

 which future management plans can be built. An additional objective was to document more 

 fully the numbers and species of bats using Azure Cave during different seasons. 



The first detailed study of bats using Azure Cave since 1978 (Chester et al. 1979) was 

 conducted by Butts (1993), who netted bats at the mouth of Azure Cave in September 1992, and 

 entered Azure Cave to obtain a count of hibernating bats in March 1993. Unfortunately, the 

 entire cave was not examined during Butts' entry, but his netting efforts and counts provide 

 additional data on timing of occupancy of the cave, and he also identified the presence of three 

 species in Azure Cave. Inventory work in 1996, conducted by the Montana Natural Heritage 

 Program (MTNHP), contributed additional data on numbers of bats using Azure Cave and the 

 timing of their occupancy, and identified water sources in the Little Rocky Mountains as 

 significant landscape features for bats (Hendricks and Genter 1997). Five species of bats were 

 captured at the mouth of Azure Cave during netting sessions in June, July, and October 

 (Hendricks and Genter 1997), and six species were identified at water sources in July, using a 

 combination of trapping and electronic monitoring techniques. Altogether, eight species of bats 



