Ornis Hungarica. vol.15-16. (2008) p.71-72.
Report on the latest results of Mute Swann (Cygnus olor) research in Hungary
The Mute Swan reappeared again in Hungary in the 1970s, after its disappearance at the end of the 19th century. Since then, it is has been spreading continuously. At first they populated the suitable waters of the Transdanubian region (Dunántúl), later they gradually spread towards the region between the Danube and Tisza rivers (Duna-Tisza köze). In the past few years, breeding pairs have already been seen in the region east of the Tisza river (Tiszántúl). The number of the breeding population was between 258-285 pairs in 2003. Their main breeding sites in the Transdanubian region are the Lake Balaton and Kis-Balaton, but they are also found on angling and fishing lakes, gravel-mine lakes, lakes with reclamation dams, and reservoirs. In the region between Danube and Tisza rivers, they also occurred on several new types of habitats (pits, saline lakes, alongside slower rivers and river bays) in growing numbers. This species appeared again east of river Tisza in the past few years, where they were also breeding on various standing waters (angling and fishing lakes, shallow swampy areas, and the Lake Tisza water reservoir). The breeding population declined in 2003. The possible causes of this decline could have been the unusually severe winter of 2002-2003 and the drought of 2003, which has led to the disappearance of some previous breeding habitats. The number of the breeding population was between 293-339 pairs in 2004. Their main breeding sites were also in the Transdanubian region. The possible causes of the growing number of the breeding pairs in 2004 were the that winter was not too severe during the winter season, and several wetlands swere occupied again. The two biggest lakes of Hungary, Lake Balaton, and Lake Velence, were previously the main moulting sites of the Mute Swans. In this period of the year in both 2003, and 2004, 600 individuals were present at Lake Balaton, and in 2003, 50 individuals were found at Lake Velence. In 2004, hardly had been moulting swans at Lake Velence. In spite of the more or less long-term continuous growing of the breeding population, this growth could not be seen in the number of the moulting individuals at Lake Balaton and at Lake Velence. In the recent years, some new moulting sites were discovered in southern Hungary, and nearby the Hungarian border in Croatia and Vojvodina (Serbia), with might indicate that the swans established moulting sites closer to the new breeding and wintering sites. During the winter, the Mute swans primarily occurred alongside the river Danube. The size of the national total Hungarian wintering population was over 1000 individuals in 2002-2003 and was slightly under 1000 in 2003-2004.