Seal pup numbers increase on Farne Islands

Press release
A seal pup on the Farne Islands
Published : 19 Dec 2018

Atlantic grey seal pup numbers at one of the largest colonies in England have reached a record high thanks to a good supply of food and lack of predators, the National Trust can reveal.

The number of seal pups born on the Farne Islands, off the Northumberland coast, has increased by 50 per cent from 1740 in 2014 to 2602[1] this year.

The grey seal is a protected sea mammal with global numbers estimated to be around 300,000 half of which live in British and Irish waters[2].

The rangers, who live on the Islands for nine months of the year, count the seals every four days in the autumn once pupping season begins, weather permitting. Once born, they’re sprayed with a harmless vegetable dye to indicate the week they are born.  Using a rotation of three or four colours allows the rangers keep track of the numbers. 

Ranger Thomas Hendry commented: “Once all the seabirds leave in late summer, our attention turns to the seals.  The seal breeding season on the Farnes is usually mid to late September until December, with the majority of pups being born in October and November.  

“We wait until the first pups are born and then begin the process of counting and marking all pups born on the Islands.  

“A lack of predators and a plentiful supply of sand eels – which makes up about 70 per cent of the seals’ diet – has helped bolster our seal pup numbers.  

“This new record for the grey seal colony is certainly a milestone and could be good news for the health of our seas around the islands, indicating a good food supply due to fishing being limited partly due to several protected areas of sea around the islands.   

“Over the next few years we will monitor the effect of a growing seal population and to manage the island habitats accordingly.”

For the first time, following a successful trial last year, rangers have also used a drone to help make the count more accurate and less stressful for the seals[3].  

Thomas continued: “The drone gives us an excellent view of the islands and from the clear images we can count the total numbers of seal pups on each island.  As the footage is taken whilst we are spraying, we use the image counts to check against the numbers we get on the ground. 

“It also allows us to see onto the smaller islands which are more challenging to land in difficult sea conditions.”

The seals are born with bright white fluffy coats.  Although the pups can swim at an early age they don’t normally leave the breeding colony until they have been weaned and after they have moulted their soft white coats.  This happens when they are about two or three weeks old and their dense grey waterproof fur grows through.

The rangers have also noticed changes to the location of the rookeries (the breeding sites).  While more pups used to be born on the islands of North and South Wamses, now many seals try to breed on Brownsman and Staple islands which are both bigger and have higher ground, therefore offering better protection from storms and high seas.

Seal pup numbers have also hit record highs at the charity’s Blakeney Point in Norfolk, where figures have reached 2,802 in this year’s count, versus 2,000 in 2014.  

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[1] Difficult landing conditions in 2017 meant that some of the islands were visited less frequently than usual so the overall figures for last year should be treated with caution as it may not reflect the true number of seal pups born that year.
Year    Number of Pups     Percentage +/-
2014    1740                        10.4%
2015    1876                        7.8%
2016    2295                        22.3%
2017    2131*                      -7.1%
2018    2602                        22.1%

[2] Globally, the Atlantic grey seal is one of the rarest seal species and about 50% of the world population lives in British and Irish waters.

[3] This year the drone has carried out 71 flights, recording 18hours 58mins of footage and covering 189,742 metres, improving the process of identifying and counting the pups across the 14 islands that make up the Farnes. 

Guillemots with an egg on the Farne Islands

Wildlife on the Farne Islands 

Puffin season is over on the Farne Islands now - they'll be back in spring next year - but there's still lots to see, including shags, cormorants, Arctic terns, kittiwakes - and of course, seals.