The spring migration and distribution of Common Crane (Grus grus) in the Carpathian Basin during the late 19^th and early 20^th centuries

During the early 21st century, the Carpathian Basin was recognised as one of the world’s most important migratory area for the Common Crane, but it is not completely clear, what was its status during the late 19^th and early 20^th centuries. Between 1897 and 1916, a total of 1487 field observation data were published in the journal Aquila from the Carpathian Basin. Our work analysed the timing of the spring migration, how it differed between years and geographical regions, and how the temperature and geographical variables reported above influenced the timing of the migration. The results show that the migration routes of the species have changed significantly over the last century. During the study period, the migration concentrated in the eastern part of the Carpathian Basin, and was particularly rare in the Great Hungarian Plain. There was on average a two-week difference in the timing of migration between the western and eastern parts and between different years. The start and peak of migration were weeks later than today, and this change is mainly due to the effects of climate change. Geographical factors did not influence the migration of the species, whereas higher air temperatures advanced the timing of the migration.