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Although many recent tracking studies have uncovered considerable variation in the migratory routines of birds, 1,2 the source of this variation is surprisingly poorly discussed. 3 We hypothesize that a wealth of possible factors, including factors other than genetics, translate into these variable outcomes. To demonstrate how factors that are not inherited can shape migratory routine during development, we performed a translocation and delayed-release experiment with juvenile, hand-raised black-tailed godwits Limosa limosa limosa that were carefully matched for ancestral background, releasing siblings 1,000 km apart. Translocated juveniles adopted the spatiotemporal pattern of migration that is habitual for the population at the release location rather than the origin. This leads to the rejection of the hypothesis that the migration of inexperienced birds is only shaped by pre-release factors, including genes, maternal material in the eggs, and a common environment from hatching to fledging. Instead, these findings are consistent with inexperienced migrants also developing their knowledge and capacities through contextual individual learning, 4 the precise nature of which now warrants study. The fact that hand-raised godwits, depending on the context in which they are released, can be induced to show different migratory routines, wintering sites, and breeding locations from their siblings indicates that processes during development offer the substrate for rapid adaptation of long-distance migration. [Display omitted] • Tracking reveals enormous variation in migratory routines, but what is the source? • Young hand-raised godwits, matched for parentage, were moved 1,000 km east • Translocated juveniles adopted the pattern of migration of the population at release • Thus, migration of young godwits is not just shaped by genes and maternal material Loonstra et al. released hand-raised godwits (matched for parentage) either at home or 1,000 km eastward, in an area where godwits show a different timing and pattern of seasonal migration. The displaced juveniles adopt the pattern of migration of the population at release. This falsifies the idea that godwit migration routines are inherited. [ABSTRACT FROM AUTHOR]