While the rest of those present, trudged round the park looking at roosts, Jude sat herself down at the point we do the Daubenton’s Count and made a continuous recording of bat activity there. ( with Jo to keep her company) using a Duet linked to a zoom recorder.
The recordings were analysed and whether a particular species was present in each 30 second segment was recorded. From this a cumulative frequency graph was constructed, which gives you a running total of the no of bats recorded.
Nothing startling, the soprano pipistrelles (green) came out first, followed by the Daubenton’s (blue) and then Noctule (red) . We only got one common pipistrelle all night.It does confirm that sampling the presence of Daubenton’s over lake 45 minutes after sunset is a good time sample. ( The recording was starting 5 minutes before sunset)
We also left a Griffin at height which picked up a few bats at canopy height. We plan to repeat this exercise again next time, as long as it is not pouring with rain. We may use a Duet at height to make a more direct comparison.
We also picked up calls from what may well have been a serotine. There were too few calls to be absolutely positive, so it is well worth another try.