Can we explain vagrancy in Europe with the autumn migration phenology of Siberian warbler species in East Russia?

Abstract

Abstract We examined the autumn migration phenology of nine Siberian breeding songbirds: Thick-billed Warbler (Iduna aedon), Black-browed Reed Warbler (Acrocephalus bistrigiceps), Pallas’s Grasshopper Warbler (Locustella certhiola), Lanceolated Warbler (L. lanceolata), Yellow-browed Warbler (Phylloscopus inornatus), Arctic Warbler (Ph. borealis), Dusky Warbler (Ph. fuscatus), Radde’s Warbler (Ph. schwarzi), Two-barred Warbler (Ph. plumbeitarsus) and compared the migration dynamic characteristics with their European occurrence time. The study was carried out within the Amur Bird Project in the Russian Far East along the river Amur at Muraviovka Park between 2011 and 2014. The birds were caught with mistnets and ringed with individually numbered rings. For the characterization of the migration, we used timing, the intervals and the peaks of the migration, the percentage of the recaptures and the average time between the first and the last captures. The timing of migration in the studied species differed in the timing, the intervals (30-67 days) and the migration peaks (14 August - 17 September). Considering the size and location of the distribution area, the timing and annual patterns of European occurrences, it is likely that most individuals of Thick-billed Warbler, Pallas’s Grasshopper Warbler, Dusky Warbler, Radde’s Warbler and Two-barred Warbler get to Europe due to the impact of Siberian cyclones. In case of Yellow- browed Warblers, other factors (reverse migration, weather conditions, dispersal movements) may also play a role. Because of their Scandinavian breeding populations, dispersion movement is the most likely reason for vagrants of Arctic Warbler and Lanceolated Warbler. The distribution of the Black-browed Reed Warbler is limited to the eastern edge of the continent, and therefore this species has no European record to date.