A dramatic rise in the number of rats is posing a major threat to birds at the area's oldest nature reserve.

The National Trust, which manages the bird-watching hot-spot at Blakeney, revealed the mild weather is behind a boom in rodents which wiped out breeding on the site in 2000.

It revealed the rats are attacking the ground-nesting black-headed gull colony at Blakeney Point and forcing the north Norfolk sandwich tern population to nest at Scolt Head Island – 15 miles further along the coast.

However, despite efforts to contain them, conservation experts admitted they were struggling to cope.

A National Trust blog revealed: 'Blakeney Point has become increasingly attractive to rats in wintertime.

'Despite our efforts, the speed of rat colonisation and reproduction has made control increasingly challenging.

'It is always disappointing when predators impact on breeding birds. Unfortunately, our persistent rat control has not been able to prevent predation and disturbance to the black-headed gull colony on Blakeney Point this spring.

'This is a conservation issue because the rare sandwich terns only start nesting after the black-headed gulls have settled, gaining protection against predators from the gulls. Consequently, there are much reduced numbers of sandwich terns present.'