Video monitoring of use of the cave by bats
It was not possible to identify the bats to species-level using the video recordings, some were shown from analysis of simultaneously-recorded heterodyne sound files to have beenRhinolophus hipposideros (and therefore removed from the analysis), whereas others were Myotis species. Overall bat activity (number of entries and exits) detected by infra-red video monitoring on 23 September 2017 was greater than that recorded earlier on 28 August (Figure 3). On both dates, bats initially left the cave (where many had been roosting) following sunset. Bats later returned to the cave, many exhibiting “chase” sequences (one bat following another) which were visible on the infra-red video recordings. From 1.5 -2 hours after sunset there was a net influx of bats into the cave.
Figure 3 : Video-evidence of bats entering and leaving the focal cave on 28 August and 23 September 2017, from half an hour before dusk, until 3.5 hours after dusk.