In which I learn I need a new approach to seeing bats

Last year I had quite a few bat adventures. I (eventually) managed to see five different species of bats, but frequently struggled with not being able to distinguish the calls captured by my bat detector. I could tell it was a species that I didn’t have ticked off my list, but not which one. So this year, I decided I needed to learn more about bats to help me in my quest.

This week I attended a Bat Ecology course, hosted by Surrey Wildlife Trust and taught by a member of Surrey Bat Group.The course was fascinating. A particular highlight was getting to see some bats up close, as there were a few captive bats present (who can’t be released back to the wild as they can’t fly properly). I learnt a lot about the different species of bats, and how to distinguish between them if I get a good view of them (when they’re not flying about in the dark). I was also reassured to learn that it’s not just me being rubbish at interpreting the sounds from my bat detector – even experts can’t tell distinguish between the Myotis bat species (Daubenton’s, Bandt’s, Whiskered, Alcathoe, Natterer’s, and Bechstein’s) using just a basic detector like mine.

So, having been reassured that it’s not (just) my incompetence that’s stopped me being able to identify some of the bats I’ve come across, I need to come up with a new way of seeing those species that I haven’t yet ticked off my list. I think I may need to start volunteering on some bat surveys.

But that’s not going to stop me walking around at night waving my bat detector in the air. Surrey’s a great place to see bats, as most of the 17-18 (it’s complicated!) British bat species are resident here. And using a detector to eavesdrop their hunting is a good way of getting a glimpse into their night time audio world, so different from our own.

More about my bat adventures:

• Bat Girl
• Bat Girl Strikes Again
• Bats of Nutfield Marsh
• More enigmatic bats
• Going bats?

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More enigmatic bats

The mad bat woman has been at it again, wondering the streets at night, waving a badly tuned radio around. This time it was a small Devon village that looked on, bemused, at my antics.

Following my recent bat walk, where only common pipistrelles came out to play, I thought I might have better luck ticking off new species from my list away from home. So I jammed my bat detector and id chart into my bag, along with a change of clothes, and jumped on a train heading west.

I was fairly confident that I would see bats, and, after dusk I was proved right, spotting my first one just a few metres from the gate of where I was staying. This time the bat detector issued a slapping, clicking sound, different to a pipistrelle. Horay, a new species to tick off my list! But what was it? My BatLib app helped to narrow the options down to three, but I really couldn’t differentiate between them, even with the help of recordings, descriptions of flight patterns and habitats. So, once again, I have seen a new species, but don’t know what it is.

A few metres round the corner I picked up some more bats. The detector made the familiar babbling, squelching sounds of common pipistrelles, but this time at a higher frequency – it was a soprano pipistrelle. Horay, a new species that I can tick off my list!
With that, I decided to call it a night. I am going to need some expert help with identifying bats. Luckily I have another bat walk with experts booked. I hope that they don’t all go into hiding like last time!

Do you have any top tips for distinguishing between bat species, using a heterodyne detector?

Bat girl

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…