Weak migration connectivity and high genetic admixture of urban-adapted Eastern Rooks (Corvus frugilegus pastinator) wintering in Korea

Global habitat loss and change reshape human-wildlife interactions, with animal migrations generating dynamic patterns of conflict. Thus, effective management of these issues requires knowledge of migratory ecology, particularly for migratory birds that strongly influence human activities, yet such information is often limited. We investigated the migration connectivity, migration patterns, and population genetic structure of the Eastern Rook ( Corvus frugilegus pastinator ), a conflict-associated urban population increasingly adapting to East Asian cities. Through hydrogen stable isotope (δ ² H) and mitochondrial DNA analyses, we examined 66 carcasses from four wintering sites in Korea. Feather δ ² H values did not differ among sites and showed no clear latitudinal trend. However, adults consistently had higher δ ² H values than first winter individuals, likely reflecting age-related differences in molt timing and location. Genetic analyses revealed high intermixing among wintering populations, with no evidence of geographically distinct breeding origins. These findings suggest that Korean wintering rooks constitute a diffuse population, implying that localized lethal control may be ineffective. Non-lethal management strategies, such as habitat modification, providing alternative roosts, and deterrence measures, should be considered to mitigate conflicts. Further research on age structure and breeding ecology is essential for identifying the causes of conflict and developing sustainable management solutions.