The world's leading scientists are increasingly mobile but those who migrate are not necessarily more productive than their stay-at-home colleagues.
Research led by Andrew Oswald, professor of economics at the University of Warwick, says that nearly half the world's most-cited physicists work outside the country of their birth, with the majority migrating to the US early in their career.
However, the analysis, which was published in The Economic Journal, also indicates that migrants and non-migrants have similar levels of productivity.
Professor Oswald used data from the Institute for Scientific Information to study the career patterns of 158 of the world's most-cited "elite" physicists. Of the sample, 61.4 per cent have worked in more than one country, and 97.4 per cent for multiple institutions.
While the physicists were born in 32 different countries, they now reside in just 16. In particular, the study identifies a "brain drain" of scientific talent to the US, part of a trend of elite physicists migrating systematically to nations with large research-and-development budgets.
Professor Oswald said that an analysis of the international movement of the elite could help forecast a country's future scientific success.
"If we believe that these very rare individuals create disproportionate benefits for society, then tremendous levels of mobility ought to be included in how we develop university funding," he said.
"The world's most important scientists gravitate to R&D spending, so as we raise or lower our science spending, we alter the flow of top scientists."
Despite this channelling of scientific talent into a small number of wealthy nations, the report states that "elite movers" are on average no more productive than "elite stayers", and that "in a world with low mobility costs, the distribution of talent can be expected to be similar across different countries".
Professor Oswald said: "One of the points we make is that in earlier decades, Nobel prizes were won more often by people who had migrated. We aren't sure why.
"Globalisation has lowered the costs of moving around the world: whereas in the old days it was only specialist scientists who moved around, nowadays it isn't."