As mentioned last year, we took an interest in bat detection:
This interest has continued through 2021 but bat sightings in and around our house have been noticeably scarcer, for some reason. The near-nightly displays by soprano pipistrelles simply haven't been replicated to the same degree, and when we do catch sight of a bat, there hasn't generally been the same pattern of intense vocalisation, presumably because the bats aren't as active in hunting.
However, on the plus side, we did successfully identify a "normal" (ie non-soprano) pipistrelle and tonight our diligence was rewarded by a clear identification of a serotine bat, a first for us. Doubtless they've always been around but a combination of size (large) and vocalisation range eliminated all other common possibilities. That's three species we've now identified with the bat detector.
From wikipedia, we learn that "the name serotine is derived from the Latin serotinus, which means 'evening'."
How lovely is that.