Bitterns are booming, conservationists say after record numbers have been heard calling for a mate.   

The birds are so shy the only way to count them is by the male's unmistakeable boom.

At the last count, in 2021, some 108 were recorded on the RSPB's reserves in East Anglia and elsewhere.

Ninety-seven were heard booming at the previous count, in 2019, while numbers have been steadily increasing since 2005, when less than 20 were recorded.

Eastern Daily Press: A well-camouflaged bittern in the reeds at TitchwellA well-camouflaged bittern in the reeds at Titchwell (Image: Les Bunyan)

Elusive bitterns prefer dense reedbeds both for cover and for their nesting sites.

The birds, which resemble small brown herons, wade through the shallows in search of fish.

Once common across the Fens and Broads, the majority now live and breed on nature reserves such as the RSPB's Titchwell Marsh, Strumpshaw Fen and Minsmere sites.

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Hayley Roan, the society's senior sites manager for north west Norfolk, said: "We had a booming male early in the season, late February and early March, but we've had no booming for the last couple of weeks.

"Visitors had some cracking views by the West Bank Path in late January and early February, but they tend to be even shyer during the breeding season."

Eastern Daily Press: A male bittern has been heard booming at the RSPB's Titchwell Marsh reserveA male bittern has been heard booming at the RSPB's Titchwell Marsh reserve (Image: Les Bunyan)

She added the reserve had one booming male last year. It was seen making feeding flights - carrying food, rather than eating it as soon as it had captured it - but no fledged birds were recorded.

Bitterns became extinct in the UK during the late 19th Century because of the loss of their reedbed habitat. 

The species returned to Norfolk in 1900, where it bred in 1911. 

Having reached a peak of about 80 booming males in the 1950s, the species started to decline again and despite a slow recovery during the 1990s, reached a low point of 11 booming males in 1997.