Separating Noctule and Serotine bats in the Field
If you hear a bat you think might be a noctule or serotine there are steps you can take to try to identify the species.
1. Pause. Walking creates a lot of noise at 25kHz so it is best to stop.
If the bat is making a two part call but when you tune the detector the deepest pitch is between the ranges of 22 and 24 kHz it could be a noctule or Leisler’s.
If you cannot tell if it is a noctule or Leisler’s bat mark as ‘unsure’.If it is definitely a Leisler’s bat with a clear two-part call during which the peak of the deepest ‘chop’ part is above 24kHz, do not record on the survey form, but make a note elsewhere.
It is difficult to be confident in separating these species and does take some practice in the field!
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