L. Forró - É. Murai szerk.: Miscellanea Zoologica Hungarica 6. 1991 (Budapest, 1991)

Bankovics, A.: Avifauna changes of the Kis-Balaton Reservoir area

Table 4. Breeding population data of some species on the Kis-Balaton Reservoir (breeding pairs) Year 1984 1985 1986 1987 1988 Species Podiceps nigricoUis - 100 150 85 50 Podiceps cristatus 10 78 105 120 130 Podiceps griseigena - 2 11Ixobrychus minutus - - - 3 4 Botaurus stellaris - - 1 1 1 Anser anser - 15 10 10 8 Anas strepera - 86 50 50 60 Netta rufina - 2 3 4 3 Aythya fidigula - 46 150 134 115 Himantopus himantopus - - 1 - Recurvirostra avosetta - - 3 - Larus ridibundus - 1800 1000 2000 2000 LOTUS melanocephalus - -44Chlidonias hybrida - 50 50 140 170 Fam. Anatidae Grey-leg Goose {Anser anser) Its breeding population has grown in Hungary since the early 1970s. Since then, it has occupied new breeding sites like the Külső-tó in Tihany Peninsula, the Kolon-tó in the Kiskunság, etc. The population date of the different sites were collected by Cs. ARADI and G. KOVÁCS in 1981. The results show approximately 600 pairs east from the Danube and approximately 200 pairs in the western half of the country in the late 1970s (ARADI & KOVÁCS 1982). The former Kis-Balaton Nature Reserve is a traditional breeding site of the Grey-leg. In 1979 about 120 pairs, in 1980 70 pairs bred (ARADI & KOVÁCS 1982). The nearby created reservoir had provided a further suitable breeding habitat, thus it was occupied by the first pairs in the first year. In 1985 15 pairs bred there. After this there was a slight decrease (see Table 4), but later the population number increased and in 1990 at least 22 pairs bred. Gadwall (Anas strepera) Since about the middle 1960s its population suffered a great decrease in Hungary. The best breeding places where this species has survived the critical years were the Csaj-tó (fishpond-system at Tömörkény) and the Kis-Balaton. Presently its population is increasing again in many other places in Hungary. At the Kis-Balaton area it had also declined in the 1960s. WARGA (1959) treated it as one of the most frequent duck species of the Kis-Balaton based on his observations in the 1940s. In March 1957 there were estimated 300 specimens during spring migration, and 700 specimens during autumn migration in 1960 (KEVE 1976). In the 1970s its number had seldom reached the maximum of 50 specimens during bird censuses. The Gadwall population has shown a growing tendency in many sites of the country in the 1980s. It was a fortunate coincidence then, the new breeding habitat was created by the inundation of the Kis-Balaton Reservoir. Just after the area became flooded they occupied it, and FUTÓ (1990) estimated eighty-six breeding