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.