Donna Nook high tides leave up to 75 seal pups dead
Up to 75 seal pups are believed to have died after a series of high tides hit a colony at a Lincolnshire reserve.
The pups were separated from their mothers at Donna Nook, near North Somercotes, by a coastal surge.
Lincolnshire Wildlife Trust closed the reserve to visitors last month to allow the seals a chance to find each other.
But the trust said while some had returned to their mothers and the colony was "recovering well", between 50 and 75 pups were still missing.
Rachel Shaw, from Lincolnshire Wildlife Trust, said when the "unusual" high waves came in they moved the seals around.
"The tide put the seals in places where they didn't want to be, it also separated the pups from their mothers and they find it quite difficult to find each other," she said.
"So if they were separated by a large distance, it might be that the pup can't find its mother again and it's abandoned."
She said the young seals were "extremely vulnerable" on their own and in the cold weather.
"These are marine mammals so they can swim and they're used to being in the water, but when they're very young, when they're just born, they're very skinny and they don't have the thick layer of blubber that keeps them warm, so they can't survive in those conditions," she said.
The trust said it was unusual for seals at Donna Nook, which is one of the largest grey seal reserves in the UK, to be disturbed by high tides.
"We haven't seen anything like this happen at Donna Nook before, and a lot of the local residents are saying that it's the highest tide they've seen in 30 years," Ms Shaw said.
Donna Nook national nature reserve, which extends along six miles of Lincolnshire coastline, is based on an active Royal Air Force weapons range.
The trust said the seals had become accustomed to the jets flying overhead, just as they have to the 60,000 visitors that come to see them every year.
For most of the year, grey seals at Donna Nook are at sea or hauled out on distant sandbanks.
However every November and December the seals give birth to their pups near the sand dunes at the reserve.
More than 1,300 pups are born annually and so far this year more than 1,000 baby seals have arrived.