Summary: the numbers relate to the number of bat passes rather than necessarily the number of bats.
Bat species = where there is insufficient information to assign the recording to a species or bat family - normally where there is too much noise to pull out a reliable signal.
Myotis species = this is where the recording belongs to the family Myotis, which in Norfolk includes Natterer's, Daubenton's, Whiskered and Brandt's.
Low confidence = where there is a high chance of the recording being assigned to the wrong species. Confusion is most likely between Daubenton's, Whiskered and Brandt's, and between Noctule, Serotine and Leisler's.
1 Brown long-eared bat
8 Common pipistrelle
2 Myotis species
28 Soprano pipistrelle
1 Brandts - low confidence
2 Brown long-eared bat
29 Common pipistrelle
1 Natterers - low confidence
36 Soprano pipistrelle
You will notice the 31st is missing; as I feared, the batteries popped out that night. The full results actually provide times of individual Bat passes more often than not down to species level. Great stuff, I could have some fun on excel if I had time or knew how! What both nights had in common was that passes stopped or went unrecorded between 2.30 and 3.00am. Not sure how to explain that, perhaps they had headed back to the roost. Certainly 5 species there, possibly 7, and as David at Wheatfen said to me it is the unconfirmed ones that are potentially the most interesting. Brandt's stands out, a Bat I have never seen and of which there are very few Norfolk records. I would expect the Myotis species on the 30th to be Daubenton's, commuting over the fen to water. Many thanks to all at the BTO for analysing the data so quickly. Remember- you can still get involved.