Förändringar i höstmigrationens tajming hos tre arter av Emberiza i Umedeltat : Skillnader mellan juvenila och adulta individer

Sammanfattning

Bird migration is a complex biological phenomenon regulated by both genetic factors and environmental factors such as photoperiod, temperature, and food availability. Climate change has been shown to influence avian phenology, particularly during spring migration, while long-term changes in autumn migration remain comparatively understudied. This study aimed to investigate the long-term changes in the central timing of autumn migration in three Emberiza species: reed bunting (Emberiza schoeniclus), yellowhammer (Emberiza citrinella), and rustic bunting (Emberiza rustica) at two bird-ringing stations in the Ume River delta, northern Sweden: Obbolatippen and T-vägen. In addition, the study examined whether the central timing of migration in autumn differed between juvenile and adult individuals. The analyzes were based on bird-ringing data collected between 2016-2025 at Obbolatippen and 2010-2025 at T-vägen. The central timing of migration was estimated using centroid day of year (centroid DOY). Temporal changes in migration timing were analyzed using linear regression models, while differences between juveniles and adults were assessed using paired t-tests. The results showed no changes in the central timing of migration over time at Obbolatippen for any of the studied species. At T-vägen a delay in autumn migration timing was observed for both yellowhammer and reed bunting. Furthermore, no differences in the central timing of migration were found between juveniles and adults for any species at either study site. This study contributes to the understanding of changes in autumn migration patterns in Emberiza spp. and highlights the importance of ongoing research on how climate change continues to affect the migration patterns of avian species in the future.