Since my first taste of bat detecting last month, I’ve splashed out on a bat detector. It’s a fairly basic heterodyne model that tuns the ultrasound emitted by bats into sounds audible to humans.
Different bat species emit ultrasound at different frequencies, and with different patterns (or tunes), so a bat detector can help you work out what the black silhouette flitting past you might be.
Since the bat detector arrived, any time that I’ve been out in the evening I’ve taken it with me. I’ve been walking around after sunset, waving what appears to be an untuned radio.
For my first expedition with it, I tried the local park. I thought the mill pond might attract bats, but no luck.
Expeditions 2, 3 and 4 involved wondering round some of the quieter roads in town, as they were on my way. Still no luck.
Finally, walking down an alleyway in town, I saw a dark shadow whizz past. I pointed the detector at it, tuned to 45khz, and started picking up some rapid clicks.
Determining which species it was is harder than I anticipated. The phone app BatLib helped narrow it down, by providing a list of bats that emit at that frequency, descriptions of their appearance, habitat and flight patterns, and recordings of what they sound like through a heterodyne detector.
Based on this, I think it’s either a Brandt’s or a Whiskered bat. But I have no idea which. To progress with my British Animal Challenge, I am going to have to find some expert help…
Wild South 
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