Return migration of German-affiliated researchers: Analyzing departure and return by gender, cohort, and discipline using Scopus bibliometric data 1996-2020.

The international migration of researchers is a highly prized dimension of scientific mobility and motivates considerable policy debate. However, tracking migration life courses of researchers is challenging due to data limitations. In this study, we use Scopus bibliometric data on 8 million publications from 1.1 million researchers who have published at least once with an affiliation address from Germany in 1996-2020. We describe several key steps and algorithms we develop that enable us to construct the partial life histories of published researchers in this period. These tools allow us to explore both the out-migration of researchers with German affiliations as well as the subsequent return of a share of this group - the returnees. Our analyses shed light on important career stages and gender disparities between researchers who remain in Germany and those who both migrate out and those who eventually return. Return migration streams are even more gender imbalanced and point to the importance of additional efforts to attract female researchers back to Germany. We document a slightly declining trend in return migration with cohorts which, for most disciplines, is associated with decreasing German collaboration ties among cohorts of researchers who leave Germany. Also, gender disparities for the most gender imbalanced disciplines are unlikely to be mitigated by return migration given the gender compositions in cohorts of researchers who leave Germany and those who return. This analysis reveals new dimensions of scholarly migration by investigating the return migration of published researchers which is critical for science policy development.