Factors related to first emergence and patterns of temporal clustering of the little brown bat (Myotis lucifugus).

Abstract

This investigation measured the effects of abiotic factors such as weather, wind, temperature, humidity, and light intensity on the time of first emergence of individual Myotis lucifugus from 3 separate maternity colonies in northern lower Michigan. None of these factors individually were found to have a significant effect on the timing of first emergence. The pattern of emergence was also examined for 2 of these colonies. The larger of the two colonies was found to have significantly more clusters occurring both before light levels reach 0 lux and before the median bat emerged. The patterns of the smaller colony fluctuated between insignificant and marginally significant differences in cluster frequencies before and after the light level reached 0 lux and the median bat emerged. These results allow a number of possible interpretations with the most plausible being the anti-predation response.