Bittern Sound Spectrogram

.. this time including the sound spectrogram that shows a quick "warm up" before the first and before the last boom. Other reedbed birds singing are  Sedge and Reed Warblers. By John Willsher recorded 24th April 2015.

Booming Bittern at Castle Water

A mono recording this morning from the viewpoint by John Willsher. The deep boom is surrounded by many Reed Warblers. You might need your headphones or bass whoofer to hear it, it's low about 30 Hz