May 13, 2013, by Kieran Cooke
Birds like this female goosander are migrating much less than formerly
Image: Tony Hisgett
EMBARGOED until 2301 GMT on Monday 13 May As temperatures climb in parts of northern Europe, some bird species, unable to find other ways of adapting to the warmer conditions, are simply not migrating as they once did. LONDON, 14 May – Most birds are acutely sensitive to changes in temperature. Scientists now say that changes in climate and warmer temperatures in parts of Europe have resulted in the migration patterns of certain birds being radically altered. A study looking at the migration patterns of three species of duck – the goldeneye, goosander and tufted duck – has found there has been a sharp decrease in the number of birds migrating south. The study, published in Global Change Biology, examined the migration patterns of the three duck species over the 1980 to 2010 period. It found that mid-winter numbers of individual ducks at the southern edge of the species’ normal distribution range – in France, Ireland and Switzerland – had dropped by nearly 120,000. Meanwhile mid-winter numbers of the species in Finland and Sweden – in areas where the ducks breed in summer – had increased by a similar amount. Chas Holt of the British Trust for Ornithology, a co-author of the study, says ornithologists in Finland were the first to notice that numbers of ducks were no longer flying south in winter. “It’s essentially a fairly gradual shift in behaviour, but it’s clear that a rise in temperatures in regions of Finland and Sweden means the ducks no longer fly south but stay closer to their summer breeding grounds all year round”, Holt told Climate News Network. Early winter temperatures in the ducks’ breeding grounds in Finland were found to have increased by 3.8°C over the 1980 to 2010 period.
Food under pressure
“There is a sharp correlation between these shifts in the range of migration and the rise in temperatures”, says Holt. “Three decades ago there would have been no open water for the ducks in winter in these north-eastern areas of their normal range. Now there is – and the ducks don’t have to move so much from their breeding grounds.” Scientists say that if increasing numbers of birds do not migrate, there’s a risk that habitats will come under increasing pressure as food supplies dwindle. They also say that while many bird species have shown an ability to adapt to changes in temperature, many may not be able to alter their behaviour fast enough if temperatures fluctuate rapidly. “What happens if there is an exceptionally cold winter in the midst of a period of relatively mild ones?” asks Holt. “Can birds such as these ducks adapt fast enough and resume their old migration patterns? “The whole issue has to be placed in context. We are seeing declines everywhere in various bird species. These changes in migration patterns also mean we have to adapt our conservation strategies as new bird wintering areas are established.” – Climate News Network
Kieran Cooke, a founding editor of Climate News Network, is a former foreign correspondent for the BBC and Financial Times. He now focuses on environmental issues