Puffin numbers have unexpectedly grown by almost one tenth over the last five years at Britain’s largest colony, a study has found.
The National Trust has declared the result of its five-yearly count of the number of the birds in the Farne Islands, off the Northumberland coast.
A nine per cent growth in numbers was recorded despite early fears during the count that the puffin population had fallen.
In fact, the birds had become concentrated on the inner Farne Isles because of a separate 50 per cent spike in the grey seal population on the outer islands, which inadvertently crush puffin burrows.
A lack of puffins on the outer Farne Isles led to initial concerns revealed by the trust last May that the population had fallen.
There were fears the cold winter, prolonged and worsened by the Beast from the East this time last year, plus a lack of food, had caused a major decline.
National Trust ranger, Thomas Hendry, said: ‘When we started the count in the outer group of islands we were very anxious that numbers were down, especially as we know puffins are struggling for survival across the globe.
‘After further investigations on the inner group of islands, numbers seemed to be much more positive. This could be due to the islands being more sheltered, providing an ideal habitat for the puffins to successfully breed and raise their young.
‘Another factor for the lower bird numbers on the outer islands could be the success of our grey seal population. We have seen seal pup numbers growing from 1,704 to 2,602 in the last five years.’
He added: ‘A rather unfortunate consequence of this growth is the seals are competing with puffins for areas to raise their young.
‘Although the two species are in residence and breed at different times of year, the weight of the seals could be crushing the puffin burrows and eroding surrounding vegetation.’
The trust said the final results of the puffin count, which involved checking a proportion of burrows on eight of the 28-island archipelago, show that puffin numbers have stabilised at around 44,000 pairs, nine per cent higher since the last count in 2013.
Numbers of puffins on the islands have increased over the past 25 years.
There were 37,710 pairs recorded in 1993 with numbers peaking at 55,674 pairs in 2003 before a sudden crash in 2008 when numbers dropped by a third, before slowly recovering.
Dr Chris Redfern, Emeritus Professor in the School of Natural and Environmental Sciences at Newcastle University, who helped to verify the figures, gave the results a cautious welcome.
He said: ‘This is good news and suggests that the population of puffins on the Farne Islands overall is at least stable at the moment.
‘However, there are indications of some re-distribution of puffins between different islands so we need to be vigilant to ensure that all islands remain in tip-top condition for this seabird to breed successfully in the future.
‘The results suggest that the marine environment off the Northumberland coast can still support good numbers of breeding seabirds, and indicate that these puffin colonies are not showing the declines recorded in colonies further north.’
The National Trust is increasing the frequency of its puffin counts from every five years to annually, to monitor the species more closely as it faces challenges including climate change, plastic pollution and availability of its main diet of sand eels.
Harriet Reid, one of the 11 National Trust rangers who live on the islands from March to December, said: ‘Annual monitoring may help us track numbers against likely causes of population change, whether that’s changes in frequency of storms and summer rainfall as a result of climate change, changes in the sand eel population or something else altogether.
‘It’s important that we contribute to the worldwide picture on puffins so that we can dig deeper into trends to really discover more about what are the key factors affecting these special birds – so we know what more we can do to help.
‘If the root causes of seabird declines are what we suspect, it will require a bigger effort to prevent overfishing, reduce our use of single use plastics and limit our use of non-renewable energy, but it can be done.’
Puffins remain on the British Trust for Ornithology’s Red List for species of conservation concern in the UK.
To survey puffins, which nest underground, rangers monitor burrows to check whether the holes are occupied or not.
A minimum of 30 plots per island were monitored, with all burrows within a 5 metre radius of the centre of the plot checked.
Signs of occupation include birds returning to nests with fish in their beaks, an indication the burrows are occupied with a hungry puffling, and external signs around the burrow such as fresh digging, puffin footprints, clearance of vegetation, hatched eggshells, or fish in the entrance.
Seal pup numbers have also hit record highs at the National Trust’s Blakeney Point site in Norfolk, where figures reached 2,802 in last year’s count, versus 2,000 in 2014.
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.
Its numbers around the UK have shot up due to lack of predators, which include whales, and a plentiful supply of sand eels, also crucial to the seals’ diets.