Autumn Visitors And Global Warming

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House martins and swallows may have departed for Africa, but last week’s stormy weather brought some unusual visitors

Autumn is well and truly here — the evenings are getting darker, leaves are changing colour, and birds are migrating.

The autumn migration began in mid-September when house martins and swallows departed for their winter grounds in the Mediterranean and Africa. Other migrants have arrived on our shores: the long run of westerly winds brought redstarts and goldcrests. More than 5,000 Brent geese arrived unusually early in Strangford Lough, Northern Ireland, after bypassing their usual stopover in Iceland from Greenland, probably because of favourable tail winds.

Last week’s stormy weather also brought some unusual visitors. After a long spell of westerly weather, easterly winds from Scandinavia and western Russia brought such birds as yellow-brown warblers that should be heading for Asia.

Bird migration patterns appear to be affected by changes in climate. Geese, ducks and swans that spend winter in the wetlands of Northern Europe are changing their migration. A study in Finland found that some species of waterfowl were migrating up to a month later than 30 years ago. In Britain the Wildfowl and Wetlands Trust (WWT) found that white-fronted geese no longer reach our shores because conditions are now improved farther north. At the WWT’s reserve at Slimbridge, Gloucestershire, the numbers of white-fronted goose from European Arctic Russia and northwest Siberia has fallen from 6,000 birds 30 years ago to about 500 now.

A study of birds flying through an Alpine mountain pass for the past 60 years found that some of them have abandoned migrating altogether, saving themselves the trouble of a long and hazardous flight.

The blackcap, a warbler with a rich melodic song, was once only a summer visitor to Britain that migrates south for winter. But now a newer population of the birds spends the winter here, after arriving from central Europe in September and October. These birds seem to enjoy our milder winters, as well as rich pickings from food left out in peoples’ gardens.

http://www.thetimes.co.uk/tto/weather/article3556152.ece