The role of professional networks and institutional prestige in shaping the first career moves of scholars.

Mobility of researchers is closely linked to knowledge diffusion, scientific innovation, and international collaboration. While prior research highlights the role of networks in shaping migration flows, the extent to which personal and institutional ties influence the direction of scientific mobility remains unclear. This study leverages large-scale digital trace data from Scopus, capturing the complete mobility trajectories, co-authorship networks, and collaboration histories of 172,000 authors over two decades (1996-2020). Using multinomial and conditional multinomial logit models, we examine scholars' first career move by (i) classifying moves into four network-defined mobility-type categories and (ii) modeling destination choice as a function of co-authorship connection strength, institutional linkages, and institutional prestige. Our findings show that not only first- but also second-order co-authorship ties-connections to a scholar's collaborators' collaborators-are a strong correlate of the direction of a move. Scholars with extensive individual professional networks, particularly those migrating abroad, are more likely to move along individual ties. In contrast, scholars from prestigious institutions, and those moving within national borders, are more likely to follow institutional routes. The destination-choice models confirm that both individual and institutional ties are associated with a higher probability of moving to specific research institutions, with a larger estimated association for individual than for institutional ones. Overall, this research provides empirical evidence on how individual and institutional connections shape scholars' first career mobility. The findings have important implications for migration theory and policy, emphasizing the need to support both individual and institutional collaboration networks to foster global scientific and knowledge exchange.