Terns feel the chill as seabird numbers rise to new heights

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Seabirds now one of Britain's greatest wildlife assets, with booming populations that are among the largest and most important in the world, an intensive survey has shown.

Seabirds now one of Britain's greatest wildlife assets, with booming populations that are among the largest and most important in the world, an intensive survey has shown.

Numbers around the coasts of Britain and Ireland have risen steadily for the past 30 years, from five million to eight million, making the British Isles one of the key seabird areas on earth. In Scotland, breeding seabirds (5.2 million) now outnumber people (5.1 million).

Remarkably, the British Isles alone contain 60 per cent of the world population of the great skua, nearly 70 per cent of the world's gannets and 90 per cent of the world's Manx shearwaters. But although most seabird species are prospering, a small number, terns in particular, are undergoing worrying declines.

The astonishingly detailed picture of the status of 25 different breeding species is contained in the report of Seabird 2000, a census of all the seabird populations of the UK, the Republic of Ireland, the Isle of Man and the Channel Islands. It was carried out between 1998 and 2002 by more than 1,000 observers who surveyed 3,200 colonies along 25,000 miles of coastline, and who also surveyed 900 colonies inland.

The results, which are due to be presented this weekend at the eighth International Seabird Conference in Aberdeen, provide a welcome relief from the gloomy bulletins of recent years; first it was announced Britain's farmland birds such as skylarks and grey partridges were in sharp decline; then it was our woodland birds, such as willow tits, that were dwindling.

In contrast, more than half of all seabird species have increased in number by more than 10 per cent in the past 30 years, and some of Britain's best-known seabirds are booming as never before, with three now over the million mark.

Top of the list is the guillemot, the cliff-nesting, penguin- lookalike, whose numbers have risen exponentially over the past 30 years. In 1969, when the first such survey was carried out, there were 650,000, rising in the mid-1980s to 1.2 million, to 1.9 million today.

Its success story is almost equalled by most people's favourite seabird, the puffin, the one with the rainbow beak, which over the same period has gone from 900,000 birds to 1.2 million. Puffins are doing particularly well on the eastern side of Britain, in such places as the Farne and Coquet islands off Northumberland.

The third million-plus species is the fulmar, the large, stiff-winged petrel whose spread around Britain was one of the most remarkable bird sagas of the past century. In 1878 they nested only on remote St Kilda, west of the Hebrides, but in the next hundred years they established themselves all around the British coastline. They increased from 600,000 birds in 1969 to nearly 1.1 million in 1985 and are now maintaining that number, indicating that they may have a reached a natural limit to their expansion.

Another species showing a great boom in numbers is the great skua or bonxie, a heavily-built gull-like predator which lives by robbing other seabirds of their fish prey, or even killing and eating them directly. It now numbers about 20,000, mainly in the northern and western isles of Scotland.

One of the principal reasons for the increases is simply that the British Isles present such a remarkable, fertile breeding ground for seabirds, said the Seabird 2000 project co-ordinator Ian Mitchell. "As a group of islands with a rich and varied coastline, we have a plethora of nesting habitats," said Dr Mitchell, from the Joint Nature Conservation Committee in Aberdeen, which organised the census with the Royal Society for the Protection of Birds and a number of other groups and agencies.

He added: "We have lots and lots of islands which are free of mammalian predators, which is where you get the largest aggregations of ground-nesting seabirds. The water around us is supplied with nutrients from the ocean currents in the Atlantic, so food is plentiful.

"You only have to go to the Mediterranean, where you have mile after mile of rocky coastlines with no seabirds on them at all, to see waters that aren't so productive. The habitats are here, the food is here and, also, we don't persecute seabirds here."

There is no doubt that seabirds are now one of Britain's principal wildlife assets, he said. Dr Norman Radcliffe, who led the RSPB team on the survey, agreed. "A visit to a seabird colony in the summer fills the senses, and these colonies provide some of the most exciting wildlife spectacles these islands can offer," he said. "The presence of eight million seabirds provides living proof of the richness of the seas around our islands. But these birds are also sensitive living barometers and the declines of some species are highly worrying." Those declines seem to be mainly affecting species which feed near the surface on sandeels, the commonest seabird meal - the small silvery fish often seen carried in the beak of a puffin.

Three types of tern, arctic, little and sandwich, have gone down significantly in numbers between 1985 and the current survey, dropping by 29 per cent, 25 per cent and 11 per cent respectively. Kittiwakes (a gull species) and shags (small cormorants) have also dropped, by 23 per cent and 25 per cent. Sandeel shortages are thought to be behind these declines, although the survey scientists stress it is too simplistic simply to blame the fishing industry, as has been done in the past. It may be to do with more complicated ecological factors, such as the depth at which the sandeels are found.

Species which are thriving, including guillemots and puffins, can dive to tremendous depths - a guillemot has been photographed by a remotely-operated submersible more than 500ft below the surface of the North Sea.

Different skills, however, are needed inland. The Seabird 2000 survey found 20,000 pairs of herring gulls nesting on rooftops in British towns and cities, double the number the last urban gull survey in 1994.

The losers...

Little tern (Sterna albifrons): Numbers have dropped by a quarter, perhaps because more chicks are being taken by foxes and kestrels

Kittiwake (Rissa tridactyla): Still the most abundant gull in the British Isles, with about 800,000 breeding birds, but numbers have fallen by a quarter

Arctic Skua (Stercorarius parasiticus) May be suffering from the bullying competition of its more aggressive relative, the bonxie

Arctic tern (Sterna paradisea): Numbers have gone down by nearly a third in the past two decades, probably because of a shortage of sandeels

...and winners

Common Guillemot (Uria aalge): Now Britain's most numerous seabird, its population has reached 1.6 million

Fulmar (Fulmarus glacialis): After a century-long expansion, the fulmar's population seems to have stabilised at just over one million

Great Skua (Catharacta skua): Also known as the bonxie, this heavily built predator and robber of other seabirds is flourishing

Puffin (Fratercula arctica): The small burrow-nester has now reached about 1.2 million around the British Isles

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