and descriptive work on the caves in the Pryor Mountain area. 

 The information derived from this project (e.g., more complete 

 temperature and humidity readings throughout the caves, as well 

 as more precise descriptions of cave structure) could provide 

 information on potential cave microhabitats that bats may be 

 using differentially, but were not possible to identify in this 

 study. It would be advantageous for this group to work closely 

 with the U.S. Forest Service and Bureau of Land Management. 



Mystery Cave has been gated in order to prevent unauthorized 

 access. The U.S. Forest Service and the Bureau of Land 

 Management may wish to consider gating other caves occurring on 

 their lands. This is particularly important in light of efforts 

 by these agencies to increase access and visitation to the area 

 by the public. Gating would assist in preserving the biological, 

 archaeological, and geological integrity of the caves in the 

 Pryor Mountains. It may be especially important for caves that 

 are occupied by the Townsend's big-eared bat, such as Four-eared 

 Bat Cave and Royce Cave. This species generally roosts in the 

 open and is particularly susceptible to disturbance (Humphrey and 

 Kunz, 1976; Kunz and Martin, 1982; Center, 1986; 1989) and may 

 abandon caves when disturbed. 



All of the caves investigated in 1990 appear to be important 

 summer habitat for bats. It should be determined if use of these 

 caves by bats is continuous or seasonal. It would therefore be 

 desirable to visit these caves during the winter to determine if 

 bats use the caves as hibernacula. Very little is known about 

 the wintering habits of bats in Montana, and in the case of 

 Myotis evotis . nothing is known about its hibernating habits 

 throughout its range (Manning and Jones, 1989) . All of the caves 

 investigated possess characteristics of hibernacula, including 

 numerous crevices and fractures where bats may roost, as well as 

 cold temperature and high humidity (Raesly and Gates, 1987; 

 Tuttle and Stevenson, 1978) . Of these. Mystery Cave and Little 

 Ice Cave may have the greatest potential as hibernacula. These 

 two caves are large and complex, and possess high humidity and 

 cold temperatures, making them potentially ideal hibernacula. In 

 three species ( Myotis volans . Myotis lucifuqus , and Myotis 

 evotis) , differential captures of males and females suggested 

 differential habitat use. At both Mystery Cave and Little Ice 

 Cave, males of all three of these species are more numerous than 

 females (Tables 8-9) . At Royce Cave, Myotis evotis was the 

 predominant species, and numbers of males and females captured 

 were nearly identical (Table 10) . The cool temperature of both 

 Mystery Cave and Little Ice Cave may preclude the use of these 

 roosts by female bats during the summer (Kunz, 1982; Anthony et 

 al., 1981) although females may occur in larger numbers during 

 winter. Royce Cave's slightly higher temperature may account for 

 the greater number of females at this location. 



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