I completed my first overnight bat survey last night, conducting a dawn and dusk survey at a warehouse site in the North-West.
Within a team of 4, each of us were designated our own section of the building to survey over both dusk and dawn periods. Equipped with the standard equipment, (detector and recording device, observation sheet) I toured my survey route over two lots of two hour periods.
Considering the building was designated as having a low probability of housing bats, there was a reasonable level of activity noted on site. During the dusk survey I heard Pipistrelle feeding and foraging on a frequent basis starting soon after sunset, suggesting a nearby roost site. Dawn activity was slower and I only recorded a handfull of pip calls. Towards the end of the survey however, I heard a fleeting call that may have been a Noctule pass however I could not say with confidence until the recordings are analysed.
After discussion with my colleagues after the survey it was agreed that there was likely a nearby roost as opposed to one within the survey site.