A special place... The Isles of Scilly are one of only two places in England where Manx Shearwaters breed

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Under threat...The Isles of Scilly hold 3,000 fewer pairs of breeding seabirds than 25 years ago

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We need YOUR help to protect our important seabird heritage

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Seabird population trends in Scilly

Seventeen species of seabird have been reliably documented as breeding on the Isles of Scilly: Manx shearwater, fulmar, storm petrel, shag, cormorant, great black-backed gull, lesser black-backed gull, herring gull, kittiwake, common tern, Arctic tern, roseate tern, sandwich tern, puffin, razorbill and guillemot (there are also three records of breeding by black-headed gull involving one or two pairs in late 18 and early 19 century but not since). Today thirteen species regularly breed. Fulmar has colonised the islands and sandwich tern, Arctic tern and roseate tern are now lost as breeding birds. The fortune of the kittiwake also remains in the balance and it could too soon be lost as a breeding bird on the islands once again.

Early accounts indicate that at least in the 1800’s the numbers of seabirds breeding on the islands were substantially higher than today with the overall seabird population potentially running into 100,000’s of birds. From 1969 onwards there have been four major co-ordinated seabird counts on the islands. Today the overall population is fewer than 20,000 seabirds on the islands, and still declining (25% since 1983). The four regularly breeding species of gull and the common terns have shown the largest recent declines of any species.

Since 2006 in addition to regular counts on some islands such as Annet, productivity monitoring has been carried out on a sample of species and islands. 

Seabird surveys across the islands were carried out again in 2015 by seabird ecologist Dr Vickie Heaney and her team. You can read the summary of the report and the updated seabird numbers on St Agnes and Gugh here and the full report here.

A brief summary of the status of the seabirds breeding on Scilly (2006).



Breeding pairs 2006

% change since SPA baseline

Long-term Trends




Continued massive increases since first breeding in 1951

European shag



Recent increase after a slow reduction in numbers through the 1980s and 1990s; still 30% more pairs than in 1969




Increased by 117% since the mid 1980s

Great black-backed gull



Recent upturn after a general decline, (down 43%) since the mid 1970s

Atlantic puffin



70% increase since the 1980s, but there is some difficulty in comparing counts

Sandwich tern



Only an occasional breeder

European storm petrel



Numbers appear relatively stable, though possibly a slight decrease2

Black-legged kittiwake



Continued decrease, reduced by 70% since 1983, and only 19% of the 1969 numbers present in 2006

Lesser black-backed gull



Continued slow decrease, down 18% since a peak of 4050 pairs in 1983

Great cormorant



Fluctuates around 50-60 pairs

Manx shearwater



Apparent recent decrease2

Common tern



Continued decrease, down 63% since a peak of 210 pairs in 1983, however an increase on the 2005 count of 67 pairs

Common guillemot



Recent decrease after a steady rise in numbers; breeding numbers have trebled since 1969

Herring gull



Continued steep decline; a 68% reduction in population since 1974


1Represents >10% of overall breeding assemblage (great black-backed gull now 9.8%).

2Based on only two counts using comparable (tape-playback) methods.


31st May 2013: The annual seabird count on Annet took place today, led by Dr Vickie Heaney on behalf of the Isles of Scilly Wildlife Trust and IOSSRP. Jaclyn and Bob joined volunteers Darren, Matt, Julian and Colin.  It was good that the weather was not too hot as this meant the impact of disturbance was kept to a minimum.

1st June 2013: On Gugh, Bob assisted Dr. Vickie Heaney with surveys of the Manx shearwater burrows on the island. Several occupied burrows were found, and one was suitable for a trial using one of our new trail cameras. Careful placement means that birds are able to land and approach the burrow unhindered – very important when you have to shuffle like a shearwater - and can also take off safely when leaving. Let’s hope we get some images of shearwaters and not rats!

Ecologists monitoring seabird populations

Volunteers assisting surveys

Principal Funders

  • Eruopa
  • Natura 2000
  • Heritage Lottery Fund

Project Partners and Supporters

  • RSPB
In addition to generous support from LIFE, the EU’s progamme for financing key environmental schemes across the continent and the UK’s own Heritage Lottery Fund, the Seabird Recovery Project is also being supported by the Isles of Scilly’s Area of Outstanding Natural Beauty Sustainable Development Fund and the Isles of Scilly Bird Group.