This was quite an interesting find as I kind of expected Daubenton's (or the 'water bat' as its commonly known) but I thought the Pipistrelles would have been Common Pipistrelles. But reading up on it I have discovered that the equally common Soprano Pipestrelle tends to favour hunting over pools and rivers. It gets its name from the higher frequency that it echo locates at, hence the reason you can differentiate the two species with the bat detector. Soprano Pipistrelle was only split from Common Pipistrelle as a separate species in the 1990s .
You can download factsheets on these species from the Bat Conservation Trust at the following link: