Rare seabirds which breed in West Sussex are believed to be at risk due to climate change.

Little terns migrate to Pagham every year to breed – but there has been just one chick fledging in the last two years.

Ivan Lang, conservation warden at RSPB’s Pagham Harbour nature reserve, said the birds – which are no heavier than a tennis ball – are under threat due to warming seas and coastal flooding.

“This winter’s weather has obviously had an impact on the little terns’ habitat,” he said.

“With warming of seas, the bait fish which the little terns feed on do not come to the surface, as they prefer the nutritionally-rich cooler water, so they are likely to move north.”

Pagham is one of less than 60 nesting sites in the UK that the species migrates to.

Predictions of increased coastal flooding and sea level rise by the Intergovernmental Panel on Climate Change could spell disaster for the seabirds.

Colonies in South Gare in North Yorkshire and Donna Nook in Lincolnshire have already been lost because of changing coastlines – and just one nesting site remains in Wales.

The RSPB is appealing to beach-goers in Pagham to give little terns space to breed undisturbed.

Susan Rendell-Read, the RSPB’s little tern project manager, said: “As climate change threatens our coastline, little terns are forced to share space on some of our most popular beaches, leading to major problems with disturbance.”