Yesterday evening I was cycling home along the river, behind the Kingsley Hotel, and the bats were out, so I decided to try recording them. I wasn’t sure if my microphone would pick them up. I couldn’t hear a thing while I recorded them. To my surprise it came out quite well!
The first section is played at 1/10th speed. You can really hear the way they’re using the sonar. The faster clicks are used when they’re honing in on an insect.
The second section is 1/4 pitch, but at normal speed, so it retains an accurate sense of movement.
I think these are Leisler Bats, but I’m not certain.