Durham Bat Group: Bat Calls
The kind of sound made by a bat can help in identifying the species you are observing.
|Serotine||9||very irregular||hand clap to "chink"||5 ms||55>25||28 kHz|
|Bechstein's||10||irregular||sharp tick||2.5 ms||110>34||50 kHz|
|Brandt's||12||regular||dull click||5 ms||65>41||45 kHz|
|Daubenton's||14||regular||flat click||6 ms||62>39||50 KHz|
|Whiskered||12||regular||dull click||5 ms||65>41||45kHz|
|2 ms||70>31||38 kHz|
|Liesler's||5||irregular||chip-chip..chop||11 ms||31>25||28 kHz|
|Noctule||3||irregular||chip-chop||14 ms||20>18||19 kHz|
|Nathusius' pip||10||quite regular||chink||8 ms||49>39 HS||39 kHz|
|Common pip||11||quite regular||chink||6 ms||55>45 HS||48 kHz|
|Soprano pip||12||quite regular||chink||6 ms||65>54 HS||56 kHz|
|10||regular||quiet clicks||2 ms||62>34||40 kHz|
|10||regular||quiet clicks||2 ms||63>30||48kHz|
|12||continuous||warbles||50 ms||69 kHz||69 kHz|
|12||continuous||warbles||40 ms||99kHz||99 kHz|
The table above is a rough guide only, as the characteristics of a bat call are strongly affected by its environment.
A bat flying in the open doesn't need to repeat so quickly, and can use a longer duration call. Calls with a duration less than about 4ms are too short to have a clear pitch and are heard instead as some kind of click; so Pips, Lieslers and Noctules have a clear pitch to their call while Natterers, Daubentons, Whiskered/Brandts and Long-eared are generally click-like with only occasional calls being long enough to have a clear pitch.
Its important to realise that the quality of a click sound will be impaired if your bat detector speaker is small (as for example some of the Ciel detectors) because the clicks have frequency components below 200Hz; so if you want to identify the bats its best to use headphones.
In the FM/CF column: 65>40 indicates a sweep from 65 down to 40 kHz; HS hockeystick; otherwise constant frequency.
Bristol's "Bats of Britain" has lots of information - including spectrograms and time expansion recordings of all the british bats (calls courtesy of Dr. Stuart Parsons).