Migration (seasonal movement) and dispersal (movement between birth and first breeding, or between breeding events) are two critical life-history decisions, both taken in response to changing ecological conditions. They could involve similar decision-making processes and covary, thereby profoundly affecting spatio-temporal population dynamics. Yet, we still know remarkably little about how migration and dispersal might be linked and affect each other. While social information (obtained by observing others’ decisions) is known to influence dispersal decisions, we do not know how such information also influences migration. Key outstanding questions are: (1) What is the metapopulation-wide association between individual migration and dispersal? (2) What is the role of early-life social environment in generating such associations? (3) To what degree does cross-season maintenance of social bonds promote concurrent dispersal and migration? To answer these questions, I will jointly quantify seasonal migration and dispersal, and links to early-life conditions and social-spatial networks, in a large-scale partially migratory metapopulation of European shags where both movements vary substantially among individuals. I will achieve these goals by applying cutting-edge statistical analyses (multi-state mark-recapture models, social networks) to an outstanding 10-year dataset comprising >90,000 year-round field sightings of ~10,000 marked individuals. My success in this novel and challenging project will be ensured by working with internationally recognized experts at world-class institutes, namely Prof. Jane Reid, Centre for Biodiversity Dynamics (NTNU, Norway) and Dr. Francis Daunt, Centre for Ecology & Hydrology (UK). I will thereby acquire all the scientific and professional skills that I require to fill a crucial gap in our understanding of population demography and its interplay with sociality, and ultimately to become a successful independent research leader in ecology.