Global warming forces Britain's birds to take flight

The Scottish crossbill may be going; the black kite may be coming. Climate change appears to be widely affecting Britain's wild birds, a study shows

Some bird populations are shrinking, some are increasing, and others are moving under the influence of rising temperatures, says the report from a coalition of conservation groups, led by the Royal Society for the Protection of Birds (RSPB).

The report has compelling evidence to indicate that although global warming is widely thought of as a phenomenon of the future, it is already changing the natural world.

Hotter, dryer summers and warmer, wetter winters are starting to affect bird numbers, and mean we may soon lose some attractive species, such as the native crossbill of Scotland's pine forests, according to The State of the UK's Birds 2004, which is being launched today at the British Birdwatching Fair at Rutland Water.

But we may gain unfamiliar, charismatic newcomers moving into Britain as breeding birds from continental Europe, such as the black kite and the cattle egret. The report, produced by the RSPB with the British Trust for Ornithology, the Wildfowl and Wetlands Trust, English Nature, Scottish Natural Heritage, the Countryside Council for Wales and the Environment and Heritage Service of Northern Ireland, pulls together a mass of recent data on changes in British bird populations which appear to be climate-related.

Although there are winners in this process, the losers attract the most concern. Global warming seems to be hitting some bird species in three ways: by directly affecting the availability of their food, by affecting the state of their habitat, and by affecting their ability to migrate.

The prime example of a food loss is with seabirds: 2004 was the worst breeding season on record for many UK seabirds, especially the guillemots and puffins of the northern isles, which suffered catastrophic breeding failure.

The nesting collapse was almost certainly down to a lack of their staple food, sandeels, and although over-fishing may be partly be to blame, scientists increasingly think sandeel populations are moving north as waters warm. Food loss may also be implicated in the decline of migrant woodland birds, returning from Africa in the spring, such as the spotted flycatcher. As springs get warmer, the caterpillars on which these birds feed their young are hatching earlier, maybe before the migrants arrive.

The effect of a warming climate on habitat seems to be having a major effect on wintering birds, and mountain birds. As Europe warms, birds which nest in the high Arctic such as the dunlin, purple sandpiper and turnstone, and which for thousands of years have come to Britain for the winter, do not need to travel so far south or west. They can spend the winter in Scandinavia, or at least on the far side of the North Sea.

Numbers of 10 wintering wader species are dropping in Britain, and are dropping faster in west coast estuaries than on the east coast. A similar effect seems to be found with wintering wildfowl, ducks, geese and swans.

The mountain birds, such as the ptarmigan and the snow bunting, and ones of the far north, such as the greenshank and the Scottish crossbill, are likely to be affected as the cool climate to which they are adapted disappears.

Winners and losers in a changing world

WINNERS

Dartford warbler (Sylvia undata) Only a few pairs in 1963 but rising temperatures are helping it spread across England. Now nearly 2,000 pairs

Black kite (Milvus migrans) A smaller relative of our red kite, this is a potential new arrival because of climate change

Cattle egret (Bubulcus ibis) May be about to repeat the performance of the little egret, which began nesting here in 1996

LOSERS

Spotted flycatcher (Muscicapa striata) A woodland birds in an unexplained decline. Could be a cater-pillar food hatching early

Guillemot (Uria aalge) The most numerous UK seabird had a disastrous breeding season because of a lack of sandeels. Sandeels believed to be shifting north because of warmer sea temperatures

Scottish crossbill (Loxia scotica) This is the UK's single endemic bird species, yet it may be driven out. Scotland's cool pine forests are warming