Hundreds of seal pups, including rare black ones, are viewed by Donna Nook visitors

The pups are normally born white before shedding their fur at two to three weeks to expose a grey coat underneath.

However, about one in 400 grey seals reveal a velvety black coat instead, and visitors to Donna Nook during the Christmas holidays have reported seeing at least a couple of these.

Thousands of people visit the salt marsh near North Somercotes each year to see, and photograph, a colony of fluffy, big-eyed seal pups from a special viewing area at the foot of the sand dunes,

In a remarkable wildlife spectacle, hundreds of seals flock to the site from the end of October to December to give birth to the pups, which remain on the beach until swimming out to sea when they are five or six weeks old.

The first pup of the 2024 season was recorded on Thursday, October 31 and, as of Friday, December 20, wardens at Donna Nook reported that a total of 1,647 pups had been born so far.

The final count for 2023 was 2,207, all bar 13 of which had headed out to sea by the first week in January. And in 2022, 2,209 were born, with the last one appearing on Christmas Day.

The coastal nature reserve, which is run by the Lincolnshire Wildlife Trust, covers 6.25 miles, or ten kilometres, of coastline between Grainthorpe Haven in the north and Saltfleet in the south.

The trust puts in place strict guidelines to ensure the safety of visitors and to reduce the possibility of disturbing the seals.

These include an insistence that no dogs or unaccompanied children are allowed in the viewing area. Flash photography is prohibited, and the seals must never be fed or petted. Mother seals may even abandon their pups if they smell of humans or dogs.

Visitors must park only in designated areas because the narrow lanes leading to the viewing area can get very congested, especially at weekends.

Britain now has 40 per cent of the world population of grey seals, meaning that Donna Nook is an increasingly important habitat.

The reserve is also well known for its array of bird life, and 47 species breed regularly there.