Gaulé has a neat article in VoxEU summarizing his recent research on the migration patterns -- actually, non-migration patterns! -- of foreign faculty members in chemistry departments in US universities between 1993 and 2010:
The incidence of return migration in my sample is low. Among foreign faculty who had their first US faculty appointment after 1993, 4.5% have returned to their home country by 2010. Using out-of-sample predictions, I estimate that a further 4.3% will return to their home country before the age of 65, assuming no change in trend in future years.
Distinguishing by source country, the incidence of return migration is relatively high for Australia, Canada, and European countries but very low for China and India. In fact, I observe only one return to India and three to China, despite the fact the Chinese and Indians are the largest groups in my sample. [Bold emphasis added]
And then, there's this:
... I find that that the most productive scientists are less likely to return.