Sex ratios for the three least abundant species in the Azure Cave samples (M ciliolabrum, M. 

 evotis, Corynorhimis townsendii), all represented by five or six individuals, favored females. 

 Why there is this difference is not clear, but it likely results from differences in roost site 

 selection and/or migratory habits between species and sexes. 



Both Myotis lucifugus and Eptesicus fuscus gained weight between summer and autumn 

 activity periods. Between June and September, M. lucifugus added an average of nearly 3 g 

 (June: 6.8 ± 0.4 g, n = 14; September: 9.7 ± 1.1 g, n = 82), a significant weight increase (/ = 

 17.58, P < 0.001). Sexes were pooled in this analysis because weight differences between sexes 

 were not statistically significant, although females were slightly heavier than males (by 0.6 g) in 

 June; each sex averaged 9.7 g in September. 



Female Eptesicus fuscus were heavier than males in September and October (t-tests, P < 

 0.01) by 2.5 and 2.6 g, respectively. There are no weight data for female E. fuscus from spring or 

 summer, but they are probably heavier than males at that time as well. There was a significant 

 correlation (/• = 0.508, P < 0.001) between September forearm length and weight for this species 

 in the Little Rocky Mountains. Forearm length of September female E. fuscus (46.9 ±1.5 mm, n 

 = 11) was, on average, significantly greater (t = 4.24, df =46, P < 0.001) than for males (45.1 ± 

 1.4 mm, n = 37). October females weighed less (21.8 ± 1.7 g, n = 4) than September females 

 (24.2 ± 2.5 g, n = 1 1 ), although the difference was not statistically significant it — 1.81, P = 

 0.093). Weight of male E. fuscus was least (Table 3) in July, greatest in September, and showed a 

 significant decline from September to October. The differences between mean weights among 

 time periods were statistically significant (Bonferroni tests, P < 0.05). 



Perhaps lighter weight in late-flying Eptesicus fuscus indicates that these individuals are 

 still attempting to accumulate fat reserves prior to hibernation. Alternatively, bats continuing 

 activity later than average may trade a loss in accumulated fat stores for increased opportunities 

 of mating. It is unlikely that late-flying bats were young of the year (see Schowalter 1980). 

 Forearm length of male E. fuscus (Table 3) varied significantly among time periods (one-way 

 ANOVA: F. M = 3.63, P = 0.0313), but October males had significantly longer forearms than 

 September males (Bonferroni test, P < 0.05). Also, most males exhibited the swollen finger 

 joints typical of adult bats (Anthony 1988). The generality of lighter weight for late-flying bats 

 of other species in the Little Rocky Mountains is not yet clear, due to insufficient samples for 

 comparisons. Schowalter (1980), however, noted similar weight loss in samples of late-flying 

 adult M. lucifugus measured after late August in Alberta, and a single male Myotis volans 

 captured at Azure Cave in October weighed 8.9 g, slightly less than the mean of 9.7 g (range 9.0- 

 10.5 g) for nine September males. 



OTHER SITES 



Two Hands Cave— This rock-shelter cave (T25N R25E S30SWSE), at 1280 m (4200 ft) 

 elevation, was first visited during July 1996 (Hendricks and Genter 1997). Pictographs are 

 present in a few places on the walls, providing the cave with its name. Eptesicus fuscus and 

 unidentified Myotis were identified with a bat detector at the mouth of the cave, and one pass by 

 the Silver-haired Bat (Lasionycteris noctivagans) was also noted. This cave was visited again on 

 8 October 1997 and 17 September 1998. Scattered bat guano was found in the cave both times, 

 to at least 11m (36 ft) from the entrance. The cave has a large opening, and ascends into the 

 hillside about 21 m (69 ft) to a small room. Woodrats (Neotoma cinerea) and feral pigeons also 

 use the cave. No bats were seen during any visit during the day, indicating it is most likely used 



