THE Suffolk coast is the most important area in the UK for one of the country's rarest birds, a new survey reveals.

The bittern, once extinct in the UK, has enjoyed its best year since records began, according to data published by the Royal Society for the Protection of Birds (RSPB) and Natural England.

Their survey uncovered evidence of 33 male bitterns at sites across the county, up from just four in 1997.

It also revealed there were 21 bittern nests in Suffolk, making it the most important county in the UK for the species – and at the top of the list of nesting sites is the RSPB reserve at Minsmere.

Ian Barthorpe, of RSPB Minsmere, said Suffolk had played a crucial role in helping the bird's resurgence, including pioneering research that established they favoured wet reed bed habitats. 'Without Minsmere bitterns would be in a much worse position than they are now, if they had been here at all. It's great news that the bittern figures are so positive, especially after the cold winters we feared might have an impact.

'We're very proud and Minsmere remains the best place to see them, especially in early summer. It's one of those birds that has a certain enigma about it and the male's booming call make it even more impressive, it's one of those unmissable sounds.'

The survey revealed Minsmere had its highest bittern population since 1976, with 11 males and six nests.

The bittern has had a roller-coaster history in Britain: after extinction in the late 19th century its numbers grew until the 1950s when its population dipped to its most recent low in 1997. There were just 11 male bitterns in 1997 but after intensive conservation efforts those numbers have swelled to 104 this year.

Martin Harper, the RSPB's conservation director, said: 'To lose the bittern once in Britain was regrettable, but to have lost it twice would have been unforgivable. Concern for the bittern in the 1990s led to an intensive species-recovery programme, with research and habitat improvement and creation playing major roles. Focused work on bitterns has led to great gains for reed beds and all the wildlife associated with this priority habitat.'

Richard Benyon MP, minister for the natural environment, welcomed the survey findings. He said: 'To see a species that was once extinct in the UK rise to a population of over one hundred is a real achievement. This is largely down to the work of the RSPB and Natural England, and shows what can be achieved if we work together.'