We occasionally see Noctule bats in Cholsey either visiting the area briefly or an individual just passing through. So when two were observed circling around just after sunset on August 30th we were in little doubt about identification. Their size and height of flight is remarkably similar to that of Swallows flying in the evening, and many could easily mistake them for Hirundines. The bat detector set for 25kHz immediately picked up their delicious calls. These are amazingly varied reflecting their acrobatic flight as they twist and turn and periodically dive dramatically to catch prey. To our suprise this first observation was to be repeated nightly for the next three weeks, noticeably earlier each evening as the daylight hours reduce. The bats stay around for up to 15 minutes and then must either return to a roost or roam further afield in search of food. It is difficult to estimate numbers since the bats are in the habit of flying well apart from each other and flying in wide circuits. We know there to be at least four. All of this strongly suggests that for the first time we have a roost quite close, possibly in a group of mature tall willows.
Meanwhile Rod D’Ayala reports something similar in his local patch in Didcot. Can it be that Noctules are faring particularly well this year? It would be interesting to know if anyone else is seeing these bats.