A collaborative team with researchers from the University of Glasgow and the University of Queen's Belfast has made a major breakthrough in the understanding of bird migration, which is particularly topical in light of recent reports of the threat of a bird flu pandemic and how it may be spread to the British Isles. The findings are to be published tomorrow, Friday 21 October, in Science journal.

The team, led by Stuart Bearhop based at Queen's University Belfast and previously at the University of Glasgow, have built on the research findings of colleagues from the Max Plank Institute for Ornithology in Germany, who were responsible for performing genetic experiments with captive birds. By cross-breeding a small type of warbler bird called "blackcaps" from Northern Europe, which migrate a long way, with birds from southern Europe, which migrate very little, the research team have demonstrated that the hybrid (cross-bred) offspring migrate half the distance that their parents did.

The findings confirm that the distance and direction that the birds migrate is controlled by the genes they inherit. However, the discovery creates a dilemma. If the new hybrid bird takes itself to a better, new, wintering area, then this inherited advantage may quickly be lost if it mates with a bird with differing genes.

The international collaborative research team has examined this evolutionary conundrum. Some central European blackcaps now migrate to spend the winter in the British Isles, while most continue to migrate to Iberia. The rain in Spain is different from rain in Britain. Iberian rainwater molecules contain more of the heavy hydrogen isotope ﾖ deuterium - than in British rain, which becomes incorporated into the birds' tissues. By catching blackcaps in spring on their breeding territories in central Europe, the researchers have been able to determine the winter location of each bird by identifying traces of deuterium taken from a tiny sample of the bird's toe-nail grown during the winter and measured by team members at the NERC (Natural Environment Research Council) Life Sciences Mass Spectrometry Facility at the Scottish Universities Environmental Research Centre.

Professor Robert Furness of the Institute of Biomedical & Life Sciences at the University of Glasgow comments:

"Our findings indicate that a new species could be created through novel migratory habits that have developed rapidly in response to climate change. The outstanding laboratory facilities of the Scottish Universities Environmental Research Centre at East Kilbride made it possible to use minute quantities of nail or feather protein to map the animals onto the isotopic pattern across Europe. This technique has enormous potential for the study of migration without the need to fit birds with rings or transmitters."

The research shows that central European blackcaps wintering in Britain mostly paired with others from Britain. This 'assortative mating' means that the migratory preference can evolve rapidly within a population due to the avoidance of random mating of different birds. Blackcaps wintering in Britain had higher breeding success rate than those wintering in Iberia, despite the warmer conditions in Iberia, so this new habit should increase.

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For further details please contact the University Press Office on 0141 330-3535, or Professor Robert Furness on 0141 330-3560.

The paper is entitled ?Assortative Mating as a Mechanism for Rapid Evolution of a Migratory Divide?. The first author is Stuart Bearhop (formerly University of Glasgow, now based at Queens University Belfast). Other authors include: Professor Robert Furness (Environmental & Evolutionary Biology); Susan Waldron (Geography & Earth Sciences); Jason Newton from Scottish Universities Environmental Research Centre; and Steve Votier (formerly University of Glasgow, now at Plymouth University).

First published: 20 October 2005