A disastrous breeding season has led to fears over the future of a famous puffin colony in the Outer Hebrides.
The puffin colony in St Kilda is under threat
A recent survey of puffin colonies found that in St Kilda substantial numbers of chicks had starved to death.
St Kilda is a world heritage site and considered the most important seabird breeding station in northwest Europe.
However, the birds' staple diet, sand eels, appeared to be moving away to cooler waters which some experts blamed on global warming.
This meant that mother birds were having to feed chicks on pipefish, which were difficult to eat because of their size and had little nutritional value.
In the past, fledging weights of puffins have been generally about 250g,
whereas the recent average weight was 157g.
It is thought that only 26% of hatched chicks are surviving this season,
compared to a normal survival rate of about 70%.
A marine warden described large numbers of "dead, downy chicks scattered on the ground" during a weekend survey on the small island of Dun which is part of St Kilda.
Sarah Money, the St Kilda ranger, said: "Puffins are usually one of the more robust of the seabirds, finding alternative sources of food when other birds struggle, so this is a really worrying sign that something is going badly wrong with the health of our seas."
An RSPB spokesman said he feared a repeat of the seabird devastation of the North Sea, Orkney and Shetland.