https://youtu.be/WJOK4kWwn6M
This audio video was broadcast and recorded by the head warden at Leighton Moss before the Corvid-19 lockdown in March and the recording is from YouTube.
This was where i saw my first ever Bittern in 1973 the year i joined the RSPB and have been an RSPB member ever since. Hope the link works. Just checked the link does work.
When I first visited Leighton Moss in 1973, there where about 13 booming male Bitterns at Leighton Moss. Sadly while the Bittern population has expanded to record booming individuals in the UK, the opposite has happened at Leighton Moss and the reason that happened has been explained before. But through the management of the Reed-Beds at Leighton Moss over the last few years, Bitterns have started to return to breed in small numbers. Hopefully they can and will get back to what the number of booming males where like in numbers, just as in the 1970’s at Leighton Moss.