To travel successfully between breeding, staging and wintering areas, migratory birds show a suite of innate dispositions about timing of movements, physiological and behavioural adaptations and the ability to orient and navigate. Despite decades of orientation research, there is an ongoing debate about the cues that migratory birds use to orient and navigate. In a classical long-term field experiment carried out between 1948-1957, Perdeck released >11.000 migrating common starlings Sturnus vulgaris of different age classes from an autumn stopover site in The Netherlands to Switzerland and showed that juvenile starlings did not adjust their migratory heading after displacement, suggesting they solely relied on a clock-and-compass system. Adult starlings, however, corrected for the experimental displacement and truly navigated to their original wintering quarters. The sensory basis of the navigational map mechanism used by these birds to navigate over unfamiliar areas is still largely unknown. The main research objective of this project is to take the Perdeck-experiment further, and investigate how birds develop navigation from a clock-and-compass system when developing from juveniles into adults using modern-day ICARUS-technology. We will track almost 1000 individual birds within a 5-year experiment where some birds are being translocated while others serve as controls. In addition to the common starling that was used in Perdeck’s original experiment, we also track similar-sized blackbirds Turdus merula, that perform a similar migratory journey, and have been the prime model species during ICARUS development. Unlike Perdeck, we track the complete migratory pathways of control and translocated birds in unprecedented detail over multiple years, which has never been done at this scale. This will teach us how clock-and-compass orientation interacts with geographical barriers and stochastic events, and develops into true navigation during a bird’s life. It will provide knowledge on migration timing and how migrating birds negotiate man-made structures and night-lit cities.