One hundred acres of Suffolk farmland are to be deliberately flooded in a bid to encourage one of Britain's rarest birds to breed.
There are only 55 breeding pairs of Bitterns in the country
The Royal Society for the Protection of Birds, using a grant from the Heritage Lottery Fund, wants to boost the number of bitterns at its Lakenheath reserve.
By transforming the fields into fen the bittern will be provided with larger breeding grounds.
There are less than 55 breeding pairs of the brown birds living in Britain.
Hundreds of acres of carrot fields have already been turned back into wetland over the past decade to create the Lakenheath Fen Reserve.
Crops have been replaced by reed beds and flood plain grazing marsh.
Jeff Kew, RSPB projects manager, said: "With the Heritage Lottery Fund's help, the RSPB has shown at Lakenheath Fen how a large area of farmland can be turned back to wildlife-rich fen land in just 10 years.
"We are delighted to receive a further grant that will help us open the reserve to local people and visitors."
The bittern, best known for its booming call, was once numerous in the fens, but is now only found in a handful of areas.
It is confined almost entirely to lowland marshes in Norfolk, Suffolk and Lancashire dominated by reeds, where it feeds principally on fish and amphibians