Phenology of Passerine bird migration in the Danube Delta, Romania

Abstract The Palearctic-African bird migration system has fascinated ornithologists for decades and is one of the most well-known. However, there is strong spatial variation in the level of knowledge, and the South-Eastern European Flyway (which passes through the Balkan Peninsula) has been studied far less than the Western European Flyway (which passes through the Iberian Peninsula and Italy). In this study, we describe the phenology of 16 common woodland species, with a detailed analysis of the pre-migration period as well as an age-specific analysis of the timing of migration. As a general trend for species wintering in sub-Saharan Africa, adult birds migrated before first-year birds, in contrast with short-distance Mediterranean wintering species, in which we observed no difference. We also provide information comparing the timing of the migration of birds with characters of subspecies of Willow Warbler Phylloscopus trochilus and Chiffchaff Phyloscopus collybita, which have not previously been reported.