Ringing of White Storks Ciconia ciconia in NE Slovenia during the 1984–2013 period

In a period of 30 years (1984-2013), 1,535 White Stork pulli were ringed on nest and 1,226 nests examined in NE Slovenia. The ringing was implemented in the regions of Dravsko polje, Slovenske gorice and Pomurje. In each season, from 9 to 85 nests were examined, the great majority of them built on overhead powerline pylons. On average, 51.16 pulli or 16.66% were ringed and 40.86 or 18.91% nests visited compared to the census of fledged pulli and inventoried nests in 1999 in NE Slovenia. A total of 71 finds or 4.6% were registered and 37 rings or 52% finds read. There were 26 (36.62%) local recoveries, while in foreign countries 34 (47.88%) recoveries of Slovenian-ringed storks were made. Two of our recoveries were registered abroad prior to 1984. There were 11 (15.49%) foreign recoveries. Local recoveries (n = 26) indicate breeding relationship (mixing) between the eastern and southern Slovenian breeding populations. The longest distance of breeding was 115 km in a beeline, the shortest 62 km (n = 4). Other 12 local recoveries at 1 to 38 km from the place of hatching concerns the native NE breeding area. Young sexually mature storks search for new breeding sites only in their fourth year of age. No ringed stork returned to the native nest as a young breeder. The oldest was 14 years old. Some of them breed in the wider area of the Pannonian Plain outside Slovenia, e.g. 3 in Austria, 2 in Serbia and 1 in Croatia. One of them bred in Slovakia 463 km away. In view of the presented recoveries it has been ascertained that the storks from NE Slovenia migrate across the Pannonian Plain, the Balkans and Asia Minor, down to the South African Republic of 8,923 km in a beeline (4 recoveries), using the eastern migration route. The western migration route was not ascertained. The majority of recoveries originated from the autumn migration period, with only one recovery known from the spring migration period. No less than 23 ringed storks, particularly young ones, were killed on migration owing to collisions with overhead power lines, which indicates inappropriate system of overhead power lines construction all over Europe.