LONDON, Nov. 21 (UPI) -- Geese, ducks and swans that spend their winters in wetlands of Northern Europe are changing their migration patterns because of global warming, researchers say.
Some waterfowl have delayed their annual migrations by as much as a month compared with 30 years ago, Finnish researchers said. In Britain, the Wildfowl and Wetlands Trust says numbers of some very familiar species are decreasing because many birds do not fly as far as they previously did, the BBC reported Monday.
In Finland, volunteers have been conducting daily bird counts since 1979 to create a "migration census" of which species were flying south from Finland and when.
"Some species had been delaying their migration dates by as much as one month," Aleksi Lehikoinen from the University of Helsinki said.
Six of the 15 species the Finnish researchers surveyed set off on their migration significantly later, including some traditional British winter visitors such as the greylag goose and the tufted duck.
"In this country, we're at the end of the flyway for birds coming down from Scandinavia, Russia and Siberia," Geoff Hilton of the WWT said. "We're almost the last stop, so some species aren't coming at all. They'll just stay further up the flyway.
"Our sense of the changing seasons is moving underneath our feet," he said. "Nature's moving away from us."
