Myotis macropus     MYMA

Steep call without any clear start or end but with a energy maximum around 40 kHz. Note the echo cloud in the spectrogram.

MmacM01101, 121229 23:44:04, Sawtell, Google Earth

In search phase there is often a clear S-form that straightens out when the bat enters a more active phase. Here are two details from the spectrogram above showing that.

Here is another feeding sequence:

MmacM01352, 121230 01:11:57, Sawtell, Google Earth

When the bat gets closer to the water surface, there will be interference between the direct and the reflected wave. Here is the impact on the oscillogram and the spectrogram.