Catches in 2017 and 2018, showed that the peak of swarming activity of Brandt’s bat occurs earlier in the season than the peak swarming activity of whiskered bats (Figure 2) but at the cave itself, very little acoustic activity was detected that could be attributed to these two species which are hard to differentiate acoustically. It is unlikely that this was due to the limitations of the Bat Classify software, as in the adjacent woodland 12.6% of Anabat Walkabout’s 87 files were identified by the Bat Classify software as either whiskered or Brandt’s bats. This shows that the calls of these two species were detectable and successfully identified by the software in the woodland; hence there was probably a genuine lack of activity by these two species at the cave. The presence of clay on one wing of both a Daubenton’s bat and a whiskered bat trapped early in the evening is highly suggestive of them having been roosting underground in the vicinity.