Study area
The study area was an area of broadleaved woodland to the North of Chepstow (Wales, UK; centred on latitude 51.6711, longitude -2.6862) on the steep sides of the River Wye valley. In the area are several natural cave formations and man-made openings in the predominantly limestone rock strata. One of these caves within the woodland (at latitude 51.67216, longitude -2.68493) has a small opening (~ 600 x 500 mm aperture) but extends a considerable distance downward (at least 50 m). This cave, referred to as “Middle Earth” in the study by Davison & Thomas (2017), has recently been shown to be a site used for swarming by multiple species of bats, including several Myotisspecies (personal observations).