80 M. D. Adam, M. J. Lacki, and L. G. Shoemaker 



relative humidity (%), average daily wind speed (km/hr), average daily 

 barometric pressure (millibars), and moon phase (% of full moon 

 illumination). 



We initially tested NDF against all environmental variables 

 separately using simple linear regression, and only those variables meeting 

 the 0.10 probability level were retained. Backwards stepwise multiple 

 regression was then used for modeling NDF against environmental variables. 

 A probability of >0.10 was used for removal of a variable from the 

 model. Data for 1990 and 1991 were combined for analysis. Differences 

 between years (sexes) were checked using analysis of variance 

 (ANOVA), with the day of sampling as a block effect. Relative humidity 

 and moon phase were arcsine transformed to correct for nonnormality 

 of the data. 



RESULTS 



All bats that were fitted with transmitters were adults except 

 for five juvenile males in August 1990 and one juvenile female in 

 August 1991. Data for body mass and reproductive condition are pre- 

 sented elsewhere (Adam et al. 1994). Transmitters did not appear to 

 adversely affect the bats. Bats showed no difficulty flying upon 

 release and were located at considerable distances from known roosts. 

 During August 1991, two females were captured which had previously 

 been fitted with a transmitter. Masses for these females were not different 

 from the average mass of other females captured during that period. 

 Although transmitters on some bats emitted signals for up to 10 days, 

 we considered 5 days to be the normal life of transmitters in this study. 

 Data from all 60 bats were used, regardless of the life of the transmitters. 



Analysis of variance demonstrated no day effect (F = 2.81; df = 

 4, 20; P > 0.10) and no interaction between day and year (F = 1.48; df 

 = 4, 20; P > 0.10). Activity rates were higher in 1991 than in 1990 

 (F = 22.9; df =1, 20; P < 0.0001) (Fig. 1). It is unclear whether this 

 difference was due to sex or varying conditions between summers, as 

 males and females were not tested in both summers. 



Bats did not emerge to forage until 30 to 45 minutes post-sunset 

 (Fig. 1). Males in 1990 exhibited a pattern with highest activity during 

 the first few hours of the night (Fig. la). The activity of females in 

 1991 was more sustained throughout the night (Fig. lb). Females in 

 these periods were either pregnant (May) or lactating (June) (Adam et 

 al. 1994), suggesting the use of night roosts and/or shorter foraging 

 bouts which allowed them to return to the maternity roost to nurse 

 their young. 



