Identify Pipistrelles and Big Bat Calls

Pipistrellus sp., Nyctalus sp. and Eptesicus serotinus have loud calls that begin with a downward FM sweep and end with a constant frequency. The CF part of the call contains the peak frequency, usually sounds considerably louder than the FM sweep, and has the quality of a prolonged slap rather than the short click produced by the FM sweep. Tuning the detector therefore allows the approximate frequency of the CF tail to be identified.