RSPB video here.
Conservation has been a success with 150 breeding males heard in England and Wales. Researchers count bitterns by the male's booming, foghorn-like call [audio]. Breeders prefers large areas of marsh that became scarce in Great Britian two decades ago. Efforts to save marsh habitat were funded by the Royal Society for Preservation of Birds and the EU. One of the wetland sites restored is near Lakenheath, Suffolk. It was a carrot field in 1995 before being converted to marsh. Bitterns began booming there in 2006. Six breeding males are now recorded on the new marsh. Somerset county is the top destination for breeding bitterns with over 40 boomers, but East Anglia remains the regional stronghold for the bird with over 80 birds. Bitterns are protected under European Union directives.