The rapid growth of England’s largest grey seal colony on the north Norfolk coast has forced a rethink on the way new pups are counted.
Pup numbers at the National Trust’s Blakeney National Nature Reserve are predicted to reach record highs this season, with more than 4,000 new arrivals expected.
This is up from just 25 pups in 2001, and 3,399 in 2019.
The success of the colony is due to low levels of disturbance and mortality during the first few key weeks of life and a lack of natural predators.
However, it is now almost impossible to record the exact number of pups.
Leighton Newman, National Trust ranger, said: “When the seals first started pupping here it was really important to count the pups to help us monitor the health of the colony.
“More recently, however, the density of the colony has increased hugely and walking through the colony is now not safe for staff or for the seals.
“Over the coming years we can hopefully push forward with this new approach but also work with experts and scientists to keep up with any other new or improved methods of monitoring this important colony.”
Until now, the pups were counted individually by rangers and volunteers walking carefully through the colony, but from this year, numbers of newborns and weaned pups will be recorded in just one specific area, giving an indication of how the whole colony is faring.
This information will be fed into the Sea Mammal Research Unit (SMRU) at St Andrew’s University in Scotland, which estimates grey seal productivity for the whole of the UK.
Chris Bielby, countryside manager for the National Trust on the North Norfolk Coast said: “Counting the colony only provides a fairly basic overview of the seal colony.
“So we are going to work with the SMRU to do more in-depth research to better-understand why Blakeney has become such an important habitat, and to look at their behaviour to get a greater understanding of these curious creatures.”
The team is also planning to work with SMRU in 2021, when they plan to do an aerial count of the seal colony.
Mr Bielby added: “It will be exciting to get an accurate picture of just how large the colony is and see if by counting just one area we can infer whether or not the colony is increasing in size.”
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