This session consisted of a seminar giving an overview of bats in the UK and some identification tips, followed by a walk around the local area of Oxford to look for bats. It was organised by Dr Marco Campera (Lecturer in Conservation and Biodiversity, Oxford Brookes University), with content delivered by Jo Harper (Warwickshire Bat Group).

Warwickshire Bat Group and

Oxford Brookes University

Bat seminar and walk

26 April 2024

The seminar presentation given provided a good overview of bats, and British bats in general. After the Discover your local bats webinar and Bats of Britain lecture I attended I was aware of quite a bit of the content though. Some interesting points from my notes include:

• The fact that tree dwelling bats may change their roost each day

• As they approach their prey, their echolocation changes and becomes longer and faster (a ‘feeding buzz’)

• In echolocation calls, a higher bandwidth (so calls being frequency modulated, FM) provides more detail but over a shorter distance. When the calls are constant frequency, CF, this provides information over a greater distance, but with not as much detail. Bat species foraging in different environments may therefore utilise these different types of call.

Seminar

For this part we walked around the local area, firstly to Headington Hill Hall. We investigated some trees that had many fissures/cracks that could have provided roosting place before walking around the site. I had a Magenta Bat5 heterodyne bat detector (Magenta Electronics Ltd., no date), that I mainly had tuned in around 45 / 46kHz – the typical peak frequency of a common pipistrelle Pipistrellus pipistrellus. At first we were a little early, probably shortly before or just after sunset, so I did not detect anything. Initially around the outside of the building and near trees to see if any would emerge from here, photos below.

Bat walk

Me using a heterodyne bat detector, Headington Hill Hall (Photo credit: Chantal Underdown)

However, away from the buildings between some trees and over some low trees/hedges I saw a bat and the detector picked it up! A common pipistrelle.

It was getting darker now and as a group we headed from this site towards Milham Ford Nature Park. Along the way we detected more bats as we went down an alleyway, and then again as we were near a construction site. In this case, as well as Pipistrelles, we also detected some Noctule Nyctalus noctule bats. These fly higher in the sky than other species and have a lower frequency than the Pipistrelles, from around 20kHz. At this point I was comparing how the heterodyne bat detector performed against the Echo Meter Touch 2 (Wildlife Acoustics Inc., 2024). This allowed the call spectrogram to be viewed and provided a potential ID. It also meant you didn’t have to scan across frequencies (as I had to do with the heterodyne detector) to pick things up. I did notice that the heterodyne detector seemed to pick things up further away that the Echo Meter didn’t, but that required some luck/judgment as to what frequency to select.

Bat detector tuned for common pipistrelles.

On the bat walk, looking near a construction site.

Finally, at Milham Ford Nature Park we stopped by a small pond in the hope that perhaps we would find something here. We did detect some bats, possible soprano Pipistrellus pygmaeus and common pipistrelles Pipistrellus pipistrellus, but they seemed to be much further away, possibly by the hedgerows. These calls were only intermittently captured by my detector.

Pond at Milham Ford Nature Park, Oxford

Reflection

An enjoyable experience, the seminar only provided a few pieces of information I hadn’t heard before, but it was useful to have it reiterated! The walk was interesting and I’m glad I got to see some bats! It was very useful to gain experience using a heterodyne bat detector and compare this to how the Echo Meter Touch 2 worked. With the display of the spectrogram, I think this tool would be easiest to use as it doesn’t require manually scanning, the only issue is whether the microphone picks everything up that maybe the heterodyne wouldn’t miss. Although, using this heterodyne required manually scanning of frequencies so there were probably things I missed as I wasn’t tuned in to the right frequency at the right time. I am considering investing in an Echo Meter Touch 2 to try and identify some bats in my local area!

References

Magenta Electronics Ltd. (no date) Bat5 Bat Detector. Available at: https://magenta2000.co.uk/product/bat5-digital-bat-detector/ (Accessed: 07 June 2024).

Wildlife Acoustics Inc. (2024) Echo Meter Touch 2. Available at: https://www.wildlifeacoustics.com/products/echo-meter-touch-2 (Accessed: 14 May 2024).