Europe has suffered a brain drain of top academic scientists that it has tried to reverse by offering better work conditions. The main competitor in the United States, where top scientists are able to attract easy funding and universities are accommodating. While pertains to relatively few people, they are considered to be key, as their reputation can attract better colleagues and graduate students, ultimately improving the rankings administrators vie for. Given the large amounts of money spent by the European Commission and its country counterparts, it is important to understand what motivates scientists to move.
Edward Bergman does this using a survey of 1800 European academics considered to be among in the top institutions. Those who exhibit higher levels of loyalty or "voice" (opinionated on local affairs) tend to stay and try to improve things internally , if necessary. The others prefer to leave when local conditions worsen, and then they have no particular loyalty to stay in Europe when they are just looking for better working conditions. All this is not too surprising. What I find more interesting is that scientists top priority is research opportunities followed by salary, and language preferences is very minor. European universities cannot count on scientists coming home any more.