Grey Seals on the Farne Islands 2015
The Farne Islands are home to thousands of grey seals, and each autumn hundreds of pups are born here.
The Farne Islands are home to individuals year round and are an ideal breeding ground for the seals, for a number of reasons. The islands have a plentiful supply of sand eels which can make up around 70% of the seals diet, although they do take a variety of fish if the opportunity arises. Secondly, the islands provide shelter in the form of haul out areas and suitable breeding sites. Disturbance from human activity is also at a minimum and so with all of these factors combined it is easy to see why the population continues to increase. This is great news for the grey seals as the UK holds 38% of the world’s population.
Grey Seals pup in the autumn months with varying start dates at different colonies. Here on the Farnes we will usually see the first pup being born in September, with the main bulk being born from October to late December. 2015 was no different with two pups discovered on the South Wamses on the 18th September. Unfortunately, as with many pups born early in the season, they didn’t survive the first 24 hours. We can only assume that they were washed away by the spring tides that we were experiencing at the time.
The season kicked off proper on the 14th October with six pups born on the North Wamses and two on Brownsman. From then on numbers rose steadily with a peak in mid-November when 187 new pups were found. Traditionally the Outer Group of islands holds the majority of ‘rookeries’ and the seals there will typically pup much earlier than those on the Inner Group. It really was a case of the rangers moving out and the seals moving in, as just a week after we moved off Inner Farne 21 new pups were found!
After our last visit on the 14th December we had a grand total of 1876 pups born around the Farne Islands. This is the highest number since the early 70’s and sees a 7.8% increase on last year.
As we reach unprecedented numbers it will be interesting to see how the population fares. We have already seen how dynamic the population between islands is, with a transfer of the main colonies from the North and South Wamses at the turn of the century to Brownsman and Staple in the current day. The former two islands had 1032 pups born whilst none were born on Staple and only 10 on Brownsman. Contrast that with 2015 and there is a dramatic difference with 655 on Brownsman, 566 on Staple, and only 489 on the North and South Wamses combined! It is thought that the reason for this is that Staple and Brownsman afford more protection to the pups and so survival rates are higher on these islands. This can also be seen in the mortality rate which was 27.5%. Although this may seem high it is relatively low considering the bad weather we have had. In the past we have seen mortality averaging at 40% when the main rookeries were based on the exposed islands of the Wamses.
Despite the wet and windy weather attempting to thwart our efforts to count the seal pups, the rangers were able to get out on a regular enough basis to carry out all of the necessary counts.