Antarctica's hungry birds seek shelter off Britain

We knew they wandered, but not this far. In a series of phenomenal journeys, the seabirds of the Southern Ocean, of Tristan da Cunha and the Falkland Islands and Antarctica, are coming to Britain and the north-east Atlantic in increasing numbers.

We knew they wandered, but not this far. In a series of phenomenal journeys, the seabirds of the Southern Ocean, of Tristan da Cunha and the Falkland Islands and Antarctica, are coming to Britain and the north-east Atlantic in increasing numbers.

Their unprecedented trips to the opposite end of the globe may be linked, some scientists think, to climate change and its effect on the productivity of plankton and the organisms at the bottom of the food chain.

Great shearwaters, which should be back at their breeding colonies at Tristan da Cunha and Gough Island in the middle of the South Atlantic, 6,000 miles away, have this month been gathering off the Isles of Scilly; more than 300 have been seen.

Sooty shearwaters, the nearest colonies of which are on the Falkland Islands 7,000 miles away, flocked to the North Sea in record numbers during September. Watchers counted 1,000 to 2,600 birds on 22 September.

And tiny Wilson's petrels, which nest on rocky, ice-free coasts of Antarctica and offshore islands 8,000 miles away, and were virtually unknown in British waters 20 years ago, have been recorded on many days between late June and September. As well as sightings off the more expected south-westerly locations such as the Isles of Scilly, Cornwall, Clare and Kerry, one was discovered 15 miles from Blyth, Northumberland, the first recorded off eastern Britain.

Black-browed albatrosses, which never normally fly north of the Equator, continue to be reported around Britain despite a declining world population. One was seen off St Kilda, the remotest of the Western Isles, in June, and another off Spurn at the mouth of the Humber last month.

The red-billed tropicbird, which nest on islands off west and north-west Africa, was recorded for the first time in British waters in 2001 off south-west England. This year there were more sightings in the same area during March and April. Fea's petrels, which also nest on Atlantic islands off north-west Africa, are showing up more often. During September they were seen off the Yorkshire, Durham and Northumberland coasts, Scilly, Orkney and Cork.

One reason for the numbers may be better bird-watching at sea. But Professor Dick Veit, an expert on climatic effects on seabird movements, believes there could also have been southern ocean climatic factors. Professor Veit, of the City University of New York, told The Independent: "There is substantial evidence from California waters and also from breeding grounds in New Zealand that sooty shearwaters declined by up to 90 per cent during 1987-1995. This is closely linked to the warming of the oceans. Such warming, and consequent reduction of planktivorous foods, might well also lead to increased dispersal and thus increased incidence in British waters."

The black-browed albatross, great shearwater and Wilson's petrel fed in Antarctic and sub-Antarctic waters in the breeding season, he added. "Those oceans have warmed in the past 30 years, and it is likely that plankton populations have declined. Whether such a shortage of food would prompt exaggerated northwards dispersal is worth considering.

"For black-browed albatrosses, we have data, based on satellite-tracking, that they respond to a shortage of food by dispersing greater distances. "

He said UK sightings of Fea's petrel and tropicbird were harder to explain because less climate change data had been collected in the tropical Atlantic. "But in the Pacific, tropical seabirds have been covering vast distances after catastrophic breeding failures associated with El Niño events."

Professor Bob Furness, a seabird expert at Glasgow University, said: "Dick's speculations are reasonable enough, but they are largely speculation. It would be worth studying whether plankton densities have decreased through the Southern Ocean and whether that is due to warming. I'm not aware of compelling evidence.

"But his point that birds disperse further if food supply is reduced is well made, and certainly true. Lots of studies show that."