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Millions of migratory birds occupy seasonally favourable breeding grounds in the Arctic1, but we know little about the formation, maintenance and future of the migration routes of Arctic birds and the genetic determinants of migratory distance. Here we established a continental-scale migration system that used satellite tracking to follow 56 peregrine falcons (Falco peregrinus) from 6 populations that breed in the Eurasian Arctic, and resequenced 35 genomes from 4 of these populations. The breeding populations used five migration routes across Eurasia, which were probably formed by longitudinal and latitudinal shifts in their breeding grounds during the transition from the Last Glacial Maximum to the Holocene epoch. Contemporary environmental divergence between the routes appears to maintain their distinctiveness. We found that the gene ADCY8is associated with population-level differences in migratory distance. We investigated the regulatory mechanism of this gene, and found that long-term memory was the most likely selective agent for divergence in ADCY8among the peregrine populations. Global warming is predicted to influence migration strategies and diminish the breeding ranges of peregrine populations of the Eurasian Arctic. Harnessing ecological interactions and evolutionary processes to study climate-driven changes in migration can facilitate the conservation of migratory birds.

We describe the migration pathways of 12 Peregrine Falcons Falco peregrinus calidusbreeding on the Yamal Peninsula, Russia. Overall, we tracked 30 complete (17 autumn and 13 spring) and 5 incomplete seasonal migration routes. Winter ranges extended from the Atlantic coast of southern Portugal in the west to Kish Island in the Arabian Gulf in the east, and from Krasnodar in southern Russia in the north to South Sudan. Eight birds were tracked to their wintering sites, with migration pathways ranging from 3,557 km to 8,114 km, taking 14 to 61 days to complete. Birds spent an average of 190 days in their winter ranges (range 136 to 212 days, N = 14), and departure on spring migration took place in April. The home ranges used by wintering Peregrines were varied including coastal habitats, agricultural landscapes, savannah, desert and an urban city. Departure from breeding areas took place in September with birds returning in May. Peregrines exhibited a high degree of fidelity to their winter ranges, with four birds tracked over three successive migrations until the 2012 breeding season.