Identify Myotis and Long-Eared Bat Calls
The calls do not show such a clearly marked peak frequency as do the calls of pipistrelles and big bats. A peak frequency, when detectable, corresponds to a broad peak on the frequency spectrum. The calls are generally quieter than the calls of pipistrelles and the repetition rate, although very variable, tends to be faster than that of pipistrelles.
Moderately loud, very regular 'clicks' or 'tocks' with rapid repetition rate (11–14 per second)**
Congratulations! You Found a Myotis Bat
Rather quiet, very regular 'clicks' or 'ticks' with a medium-rapid or very rapid repetition rate (9–15 per second)
Long-Eared and some Myotis Bats
Note that there is not a complete separation between these two options. Natterer’s Bat, in particular, can key out to either option.
** The Greater Mouse-Eared Bat (so rare in Britain as to be scarcely worth considering) should key out here. The sound of the calls is moderately loud tocks with a medium repetition rate, usually regular in rhythm, but occasionally erratic in the same pattern as a pipistrelle. The peak frequency is about 30 kHz.