These instructions are for identifying bat species using a tuneable heterodyne bat detector, such as a Magenta or Batbox.
- Bats tend not to use their most distinctive calls as they emerge from a roost and this can make identification challenging.
- Therefore, when listening on a bat detector, stand back from a roost while still close to the bats’ flight
- path and with their calls still clearly audible on the detector.
- If possible aim to listen to the bats where they are flying in a more open environment, i.e. in a clear open space or close to trees next to an open environment.
| Species common name | Call characteristics | Possible confusion species |
|---|---|---|
| common pipistrelle | Peak frequency between 42-48 kHz Irregular rhythm Wet, slappy sound Moderately fast pulse repetition rate/about 10 pulses/sec | When emerging or close to clutter, peak frequency can overlap with that of soprano pipistrelle in a very open environment (around 50 kHz). In such situations, can also sound similar to Myotis species, such as Natterer’s bat. |
| soprano pipistrelle | Peak frequency >52 kHz Irregular rhythm Wet, slappy sound Moderately fast pulse repetition rate/about 10 pulses/sec | When flying in very open environment, peak frequency can overlap with that of common pipistrelle in clutter (around 50 kHz). When emerging or close to clutter, can also sound similar to Myotis species such as Natterer’s bat. |
| brown long-eared bat | Peak frequency at about 33 kHz Very soft purring sound, only detectable within about 5m of bat. Fast pulse repetition rate/about 13 pulses/sec. | When flying in a very open environment, peak frequency can overlap with that of common pipistrelle in clutter (around 50 kHz). When emerging or close to clutter, can also sound similar to Myotis species such as Natterer’s bat. |
| Natterer’s bat | Peak frequency of about 47 kHz. Series of rapid, dry clicks producing a crackly sound. Irregular rhythm. Fast pulse repetition rate/about 13 pulses/sec. Calls can be heard through a very wide range of tunings (sometimes as high as 145 kHz or as low as 15 kHz). | Can sound similar to Myotis species, but much quieter. Not possible to separate from a grey long-eared bat based on calls. |
| serotine | Peak frequency between 25-29 kHz. Tock sound. Irregular, funky rhythm. Relatively slow repetition rate/about 5 pulses/second. | Noctule and Leisier’s bat. These have narrower wings and will produce a more regular chip-chop call as they move into the open. |
| lesser horseshoe | Peak frequency around 111 kHz Continuous warbling sound | No confusion species. Sounds very similar to a greater horseshoe bat, but at a very different frequency. |
| greater horseshoe | Peak frequency around 81 kHz Continuous warbling sound | No confusion species. Sounds very similar to a lesser horseshoe bat, but at a very different frequency. |
Above text and images taken for JNCC leaflet for NBMP – “Roost Count – how to separate species using a bat detector” – April 2013