Rafał Bobrek, Tomasz Wilk, Aleksandra Pępkowska-Król
Ornis Polonica 2019, 60: 181–196
https://doi.org/10.12657/ornis.2019.3.1
Abstract: The paper presents the results of counts of corvids in the Polish Carpathians, conducted in autumn (2011–2013) and spring (2015) in 28 and 12 observation points, respectively. Based on the seasonal dynamics of bird observations, changes in the flock sizes and recorded flight directions, an attempt was made to assess whether the seasonal migration of particular species occurred in the region. The results indicate the existence of a clear passage of the Jay Garrulus glandarius in spring, as well as the Jackdaw Corvus monedula and Rook C. frugilegus in autumn, with only the latter species migrating intensively. The directions of flights allowed to assume that Jackdaws and Rooks migrating through the studied region could reach both western and southern European wintering grounds. These two species passed through the Carpathians probably also in spring, but at that time of year their migration was weakly marked. The autumn migration of Jays is likely, but not certain. We did not find convincing evidence for the passage of three species (Magpie Pica pica, Raven C. corax and Nutcracker Nucifraga caryocatactes) considered as non-migratory. The seasonal changes in the frequency of observations of these three species may be explained by the changes in their activity, behaviour or flocking tendency across the year. The pattern of the Hooded Crow C. cornix records was difficult to interpret, and did not allow for a reliable assessment of its migratoriness. Seasonal dynamics of the increased observation frequency of Jay and Nutcracker in the Carpathians coincided with the peak periods of the invasive movements of these species recorded in Central Europe. However, no significant differences were found in the abundance of these species between the study seasons.
Keywords: Corvids, directions of passage, migration, migratoriness, mountains, nomadic and invasive movements, sedentariness
