Kittiwakes are among the birds to have declined
Experts said they have noticed a drop in the numbers of some seabirds at an important site on the Cumbrian coast.
St Bees Head is a key location as it is the only area of cliffs on the coast of the north-west of England.
The RSPB said the populations of fulmar and herring gulls at the site had fallen by about 25% and kittiwake numbers had also dropped.
It came after a report by Scottish Natural Heritage said Scotland's seabirds fell by 19% from 2000 to 2008.
The RSPB has just completed its third and final count of the year at St Bees Head
Site manager Norman Holton said: "We have noticed a couple of species that are well down - the fulmar and the herring gull - their populations have declined at this site by somewhere around 25%.
"The kittiwake, we normally have around 1,300 pairs nesting this year we have got below 1,000 so they're declining."
Matt Parsons, who coordinates the National Seabird Monitoring Programme, said nationally since 1986 there had been a drop of about 9% in the total number of seabirds and in some areas it was higher.
He said it was not a simple picture but was largely down to the availability of food.