A bittern taking flight in Somerset. Photo: Gareth Fuller/PA Wire

Once-extinct bitterns are bouncing back as a breeding bird in the UK, conservationists said after more than 150 males were recorded in surveying this year.

The bittern, a type of heron known for the “booming” call of the males, were extinct in the UK at the turn of the 20th century but saw numbers grow to around 80 males in the 1950s and then fall again to just 11 males in 1997.

A concerted conservation programme reversed its second slide towards extinction and more than 150 males have been recorded so far this year – an exceptional year in recent times, and thought to be the highest numbers since the early 19th century.

The elusive bird, which was absent as a breeding bird altogether between 1870 and 1911, needs large areas of wet reedbeds to thrive, and conservation work has focused on restoring swathes of the habitat in East Anglia and Somerset.

Simon Wotton, RSPB conservation scientist, said: “In the late 1990s the bittern was heading towards a second extinction in the UK, largely because its preferred habitat, wet reedbed – was drying out and required intensive management, restoration and habitat recreation.

“But thanks to efforts to improve the habitat, combined with significant funding from two projects under the European Union Life Programme, the bittern was saved, and we’re delighted that its success keeps going from strength to strength.

The wildlife charity’s conservation director Martin Harper, said: “The bittern is a species which proves that conservation can be successful, especially when you can identify the reason behind its decline and bring in measures and funding to aid its recovery.”

But with more than half of the booming males identified this year on sites protected under international law, namely the EU’s Birds and Habitats Directives, conservationists are concerned about the impact that a review of the laws could have on wildlife.

Harper said: “These sites have been vital to the conservation of the bittern and other key species in the UK.

“However, the European Union is consulting on the future of the Birds and Habitats directives, and we fear this may lead to a weakening of the directives, with potentially disastrous consequences for many threatened species.”

Significant conservation projects have included Ham Wall reserve in Somerset – created from old peat workings from 1995; carrot fields transformed into wetlands at Lakenheath in Suffolk; and Ouse Fen in Cambridgeshire, created at a gravel extraction site, which over time will become the largest reedbed in the UK.

All three sites have attracted bitterns, with males recorded booming in their reedbed habitat.

The figures show that Somerset is the top county for bitterns since they became re-established there in 2008, with more than 40 booming males this year, while East Anglia remains the bird’s stronghold, with more than 80 booming males.

Bitterns are particularly found in traditional sites on the Suffolk coast and in the Norfolk Broads – but are also increasingly being recorded in newly-created habitat in the Fens, the RSPB said.