Scottish Natural Heritage (SNH) said the major cause was almost certainly a shortage of food due to a drop in the number of small fish, such as sandeels.

"In the past decade the hopes of a good breeding season have been crushed, as eggs are deserted or young chicks starve in their nests because the adult birds cannot find enough fish."

Doug Gilbert, an ecologist with RSPB Scotland, said: "Regrettably the poor breeding performance of our internationally important seabird colonies is now an annual theme.