Spanish immigrants fleeing poor living conditions have dodged UK border control and set up camp at Cliffe Pools on the North Kent Marshes.

But before Nigel Farage dons his waders and stands for election there, he should be warned: the only votes he’ll get against these incomers are from the invertebrates living on the lake’s muddy shores – the main diet of the rare black-winged stilts.

The avian invaders have landed at Cliffe Pools and the RSPB’s newest reserve in West Sussex, Medmerry, and are now attempting to nest – causing a stir among environmentalists and bird watchers around the country.

The only times black-winged stilts have previously bred successfully in the UK was in Norfolk in 1987 and Nottinghamshire in 1945. But it is thought the birds – driven here by a dry spell in southern Spain – could become more frequent visitors due to climate change.

The RSPB has set up a 24-hour watch on the nests with the help of volunteers, protecting them from egg collectors and giving them the best chance of rearing their young.

“This is really exciting news and the first time we have had black-winged stilts breeding on the reserve,” said Cliffe Pools warden Andy Daw.

“They have visited before and a pair was seen about seven years ago but they did not produce any young.

“The eggs are due to hatch in June and we are doing everything we can to make sure this is a successful breeding attempt.

"The other pair is in undergrowth and we have not confirmed yet that they are nesting.

“The breeding pair is visible through telescopes and binoculars. The fact they are on an island is helpful because there is less risk from predators.”

Gwyn Williams, the RSPB’s head of reserves and protected areas, said: “With a changing climate we’re anticipating that several more southern European bird species may colonise southern England in the next few years, following on from the already-established little egret and more recently great white egret.

“So we’re planning for their arrival by creating and managing the ideal conditions on our nature reserves.”