Autumn flight activity of the greater horseshoe bat at hibernacula

Abstract

The activity patterns of vespertilionid bats at the entrances of hibernacula in temperate zones have been investigated on many occasions. However, little is known about nocturnal flight activity in autumn and its function in horseshoe bats so far. Here, we have recorded the autumn flight activity in and around the entrances of hibernacula of greater horseshoe bats,Rhinolophus ferrumequinumby behavioural observations, mistnetting, and acoustic surveys for two consecutive years. Greater horseshoe bats not only chased each other around cave entrances but also entered and left the entrance frequently. However, no mating events were directly observed in this study, normally a prominent part of swarming behaviour in vespertilionids. Therefore, it is difficult to deduce the function of the autumn flight activity of the greater horseshoe bats at hibernacula from the present data. Additionally, the recorded flight activity was positively correlated with ambient temperature and humidity. To our knowledge, our study provides the first detailed record of the pattern of autumn flight activity in horseshoe bats, and suggests that weather conditions may impact the bats’ nocturnal flight activity.