The RSPB says that Scilly is the most significant seabird colony in the southwest.
Their statement follows the release of data collected during last year’s seabird survey, the most detailed for nine years.
Volunteers counted breeding seabirds on over 60 different rocks and islands across Scilly.
The survey has found that Scilly supports over 8,000 breeding pairs of 13 species of seabirds.
Among the winners are Manx shearwater, whose numbers have trebled since 2006.
Guillemots and razorbills are increasing in number too and there’s been no change within the islands’ puffin population.
But herring gulls, lesser black-backed gulls and shags have suffered losses of over 20% in the islands in the last nine years.
And the numbers of common terns and kittiwakes are also now low.
That follows a national trend and there is concern that they may soon be lost as regular nesting species.
Overall the number of seabirds breeding within Scilly has decreased by almost 10% since the last major survey and the RSPB says that this rapid rate of loss could represent a wider issue with the health of our oceans.
Scilly-based RSPB Project Research Officer Vickie Heaney says: “We have a great set of data on seabird numbers in Scilly with regular all-island counts completed since 1970. Having coordinated the surveys in 2000 and 2006, it has been a real thrill to carry out these surveys once again.”
Recently St Agnes and Gugh have been declared ‘rat free.’ That follows an organised campaign to poison the rodents in order to protect breeding storm petrel and Manx shearwater from the predators.
Seabird Recovery Project Manager Jaclyn Pearson has appealed to islanders and visitors to St Agnes who think they might have spotted a rat to call the project ‘Rat on a Rat’ hotline on Scillonia 422153.