Rafał Bobrek, Tomasz Wilk, Aleksandra Pępkowska-Król
Ornis Polonica 2017, 58: 143–159
https://doi.org/10.12657/ornis.2017.3.0
Abstract: The paper presents the parameters of Common Crane Grus grus migration in the Polish part of the Carpathians. The influence of weather on migration intensity was also analysed. The bird migration was visually monitored in observation points in autumns 2011–2013 (28 points) and in spring 2015 (12 points) distributed across the whole region. The spring and autumn passage concentrated in the eastern part of the Carpatians, although minor but distinct migration stream was recorded in autumn also in the west. Spring migration lasted at least 43 days (8 Mar–19 Apr), and on average 33.9 ind./10 h were recorded in single location. Mean and largest flock size comprised 61.9 (Me=53) and 292 birds, respectively. Almost all Cranes migrated in the N and NE direction. Autumn migration lasted ca. 80 days (24 Aug–11 Nov), but the passage was less intense – 15.6 ind./10 h of observation. An average flock consisted of 28.9 (Me=24) birds and the largest had 222 birds. Cranes migrated mainly in the S and SW direction, but in the western points the W direction prevailed. The migration peaked around the midday in spring or in the late afternoon in autumn. The seasonal peak of migration occurred in the middle of March and in the last decade of September. In comparison with 1960s and 1980s the timing of both peaks of passage has advanced, and autumn migration period has extended as a result of an earlier start. In autumn birds preferred good visibility and moderate wind force. As much as 69.2% (spring) and 87.6% (autumn) of flocks migrated using an active flight.
Keywords: dynamics and phenology of migration, migration barrier, mountains, weather conditions
