THE INFLUENCE OF MOONLIGHT ON THE ACTIVITY OF LITTLE BROWN BATS (MYOTIS-LUCIFUGUS)

Lunar cycles influence the activity patterns of a variety of organisms including marine fish, rodents, birds, and fruit-eating bats. Lunar l ight, specifically a full moon, has also been suggested to depress the activity of insectivorous bats, because of increased predation risk o r decreased insect prey abundance. These observations are generally an ecdotal, however, with few quantitative data to support or refute them . The purpose of our study was to measure activity of little brown bat s (Myotis lucifugus) in relation to the lunar cycle, and other environ mental conditions, (e.g., ambient temperature, cloud cover, and wind s trength). If bats are ''lunar phobic'' for predator avoidance reasons, then activity levels should decrease or shift to more sheltered habit ats. We used ultrasonic bat detectors to assess bat activity. Counter to our prediction, the percent moon face illuminated did not significa ntly predict bat activity levels There was also no evidence of a habit at shift correlated with lunar light levels. Activity was significantl y related only to ambient temperature, a result commonly found in othe r studies. Our results indicate that insectivorous bats are not lunar phobic, implying they do not experience substantially higher predation risk or lower prey availability during moonlit periods.