Wildfowl numbers in the Firth of Forth are steadily declining, and the experts are worried

Seagulls might not be viewed with any sympathy by city centre residents, who see them as bin bag pillagers and the source of an unwelcome, screeching dawn chorus.

But the Firth of Forth's wider seabird population is in trouble. It is one of many areas around the UK which have seen seabird populations dropping for years, prompting the RSPB to warn that these "alarming declines" herald a worrying summer for Scotland's colonies.

Figures just published by the Joint Nature Conservation Committee show that the number of breeding kittiwakes around Scotland fell by 40 per cent between 1999 and 2009, while fulmar numbers declined by 38 per cent and herring gulls by 43 per cent.

Rory Craford, policy officer for Royal Society for the Protection of Birds, said the picture was "mixed" for Scottish seabirds across the board.

"The major issue has been food supply and not the right amount of sand eels," he said. "It seems that has been driven by climate change. There has been a huge reduction of plankton in the North Sea and Firth of Forth which is the food of sandeels which may have contributed to their decline. Kittiwakes and Tern are heavily reliant on sand eels for food whereas other birds can dive into the water column."

The RSPB's concerns are echoed by staff of the Scottish Seabird Centre in North Berwick, where experts monitor the populations of birds in the Forth, not only via carefully-placed remote cameras, but with a range of in-depth research projects.

Chief executive, Tom Brock, says the centre has seen declining bird numbers for many years: "We've been open 10 years and we've certainly seen changes in that time. Seabirds tend to be long lived, 20, 30, 40 years, so taking one season in isolation doesn't show you what the trends are.

"From a national perspective, across Scotland we're extremely concerned about the future of Scotland's sea birds and considering Scotland's got almost half of all the seabirds nesting in Europe, it's an international impact."

Species which are particularly struggling in the Forth include kittiwakes, puffins and fulmars.

Mr Brock says: "We're extremely concerned. Threats to seabirds come from lots of different areas, one seems to be local shortages of food and this seems to be caused by the seas warming up slightly, due to climate change, and prey species changing as a result.

"Sand eels are moving northwards and being replaced by pipefish moving in from the south, which are not really suitable food for many species. What we've seen on the live cameras is that we have chicks dying of starvation and the parents trying to feed pipefish to them and they choke, or starve to death."

This is particularly a problem for species like puffins which can't fly far to feed, and are dependent on local stock. Other birds, like gannets, are more resilient because they are capable of long-distance flight, and will go as far as Norway to feed.

However, even they don't find it as easy to feed as they once did, Mr Brock says: "The gannets on the Bass Rock seem to be performing quite well just now, but we're doing quite a lot of research with universities and they're being satellite-tracked, and they are having to travel further afield to catch their food and that would have an impact."

The centre has also lobbied to prevent what it sees as another potential catastrophe for seabirds - the possibility of oil transfers in the Forth. Plans for new restrictions on ship-to-ship oil transfers have been thrown into doubt by the coalition government, which has announced that it intends to carry out a review of the issue.

And even for people motivated only by economic self-interest, he says there are good reasons to care for our seabirds: "One thing that's been a huge success story for Scotland is a growth of wildlife tourism. A recent report showed that it was worth 65 million per annum across Scotland, and there are 2,700 full time jobs dependent on wildlife tourism. Obviously, if we don't have wildlife, we don't have the wildlife tourism."

There are small pieces of good news. More than 500 volunteers have been working to cut back tree mallow plants on the island of Craigleith, which had grown so dense that they prevented puffins from reaching their burrowing sites. It is early days, but the eyes of the Seabird Centre staff have been keenly trained on the Craigleith cameras, and they say signs are so far encouraging.

It is positive news, but it seems it will take more than just small-scale efforts to turn around the decline in our seabird populations - a fundamental change in attitude is needed from both the public and politicians, before it's too late, according to Mr Brock: "The key thing is that we all need to value what a special thing we've got around our coastline, and the government have to recognise that."