Part of bird reserve left to sea

One of the biggest bird feeders in the world was built at the reserve

Part of one of Britain's most important bird reserves is to be abandoned because of coastal erosion.

Up to a third of the RSPB's Titchwell Marshes on the north Norfolk coast will be given up to protect the rest of the sanctuary from the encroaching sea.

Salt water would damage the freshwater habitat at the reserve, which is home to rare species including bitterns, bearded tits and marsh harriers.

The RSPB says it will spend £1.5m on a managed retreat and new sea walls.

The erosion of the coast has put the reserve's mixture of brackish marshes - salt marshland which is diluted with freshwater - freshwater marshes and reedbeds at risk of inundation, threatening the resident birds.

We faced a stark choice between sacrificing the brackish marsh or losing the whole site to the sea Rob Coleman Reserve manager

At any time, high tides and storm surges could breach the current sea walls which protect 56 hectares (138 acres) of the site.

The managed retreat will see 11 hectares (27 acres) of brackish marsh return to saltmarsh and mudflats exposed to the tide.

Rob Coleman, the reserve's manager, said the need for the scheme "was clear".

"We faced a stark choice between sacrificing the brackish marsh or losing the whole site to the sea."

Climate change

The RSPB's Helen Deavin, project manager of the managed retreat, said the scheme should ensure the reserve is protected for 50 years, when the natural erosion process is expected to move further down the coast.

"We've got to bear in mind the impacts of climate change such as sea level rises along the coast and increased storminess. These problems aren't going to go away," she added.

But despite losing the brackish marsh, the newly-created intertidal saltmarsh and mudflats will also become important habitats for birds, the RSPB said.

The charity is also planning to create more island nesting sites for breeding avocets in the freshwater part of the reserve and at the Freiston Shore and Frampton Marsh reserves, about 19 miles away.

Four more hectares of reedbed for bitterns will also be created.

The site, visited by around 90,000 people a year, was a tank range during World War II and the site of a military hospital.