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Northern birds make better mates

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21.10.2005

Joint press release: Natural Environment Research Council and Queen’s University Belfast

Research from Queen’s University Belfast, published today in the journal Science, has given new meaning to the ‘north-south divide’. It has shown that one breed of European songbird is bucking the trend to travel south for the winter and is opting to migrate to the chillier climes of Britain and Ireland instead. The research also indicates that birds over-wintering in the British Isles produce larger clutches and more young than those migrating further south.

Led by Dr Stuart Bearhop, from the University’s School of Biological and Food Sciences, the researchers analysed the chemical patterns in toenails clipped from migrating blackcaps in a bid to find out what they had been eating - and hence find where they had been spending the winter.

Dr Bearhop said, "It has proved very difficult to investigate the reasons behind this change because these birds are hard to follow all year around. By analysing the chemical patterns in toenail clippings my team has been able to discover where the birds arriving at their summer breeding grounds in Austria and Germany have spent the winter.”

"We found that birds which spent the winter in Britain are more successful breeders than their counterparts which travelled to southern Iberia and North Africa - the more usual winter habitats for the blackcaps. We also found that the ’British’ birds tend to arrive on the breeding grounds earlier than the southern ones, allowing them to gain access to the best territories - a bit like getting their towels on the best sun-loungers first," he said.

The research uncovered a new migration and mating pattern for these birds, finding that blackcaps that head north for the winter are more likely to mate with each other during the summer breeding season than with birds that winter in the south. Known as assortative mating, this could shed new light on the gradual evolution of species.

Dr Bearhop believes that the results also indicate a way in which migratory species can respond to climate change.

"Our findings may provide hope for some species since such migratory shifts may be one way in which birds might find more suitable conditions in which to breed or spend the winter," he said.

Funding for the research was provided by the Natural Environment Research Council (NERC).

The research team includes colleagues from the Max Planck Institute for Ornithology in Radolfzell, Scottish Universities Environmental Research Center, Universities of Glasgow and Plymouth.

Marion O’Sullivan | Source: alphagalileo
Further information: www.nerc.ac.uk

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