Examination of bats in the hand.
All bats caught for this study were trapped under a licence issued by Natural Resources Wales (licence no. 73106c:OTH:SRAB:2017). Catches took place on multiple nights during the swarming seasons of 2013 and 2018, in four different areas of the woodland around the focal cave (“Middle Earth”). All catches were made within ~100 m of the cave entrance. Bats were only trapped at the cave entrance on two occasions, so as to minimise the possibility of bats in the traps echo locating and being detected by the bat detector at the cave entrance, thereby falsely elevating the number of calls recorded. Alternatively, the presence of the trap may have acted to keep bats away from the cave and therefore reduced the number of calls recorded. Trapping sessions ran from sunset until bat activity declined substantially (in the early hours of the morning). The exceptions were the nights of 22 September 2017 and 12 September 2018, when on both nights trapping terminated at 22.00 GMT even though activity at the time was high.