Bitterns and Other Birds: Ham Wall 20 April, 4 am
A sound that has been absent from the levels for over forty years has returned .
Just before sunrise the wetlands of Ham Wall reverberate with the booming mating calls of the male Bittern. The bird builds up to the weird low frequency woosh of sound with a series of wheezing and cough-like noises. It is now possible to stand on the banks of one of the lakes as the first glimmers of dawn touch the sky, surrounded by a symphony of low frequency booms underpinning and far below the rest of the dawn chorus.