Vig Károly: Zoological Research in Western Hungary. A history (Szombathely, 2003)

Phylum Vertebrata 187 bundus) were summarized by PÉTER BERETZK (1942b). It breeds in varying numbers (100-2500 pairs) on the Fertőújlak habitat-reconstruction area, but the population is tending to decline. The fourth certified occurrence of the slender-billed gull (L. genei) in Hungary was recorded near Fertőújlak on May 30, 1998, when the bird remained in the area until June 4 (HADARICS 1999b). Several weather fronts had passed over Central Europe from the south-west before its appearance, and as with the cattle egret (Bubulcus ibis), such a front had probably brought it from the Western basin of the Mediterranean (see HADARICS 1999a). An occurrence of the yellow-legged gull (L. cachinnans) at Neusiedl am See (Nezsider) was recorded as L. argentatus michahellis by KURT BAUER (1953). The earlier division of the herring gull (L. argentatus) into 14 subspecies has since changed and most of the occurrences of the subspecies recorded by BAUER have been transferred to the new yellow-legged gull species. (L. cachinnans), although some authors have retained the subspecies designation (L. cachinnans michahellis). The yellow-legged gull has bred regularly in the Seewinkel since 1987 (DVORAK et al. 1993) and a pair was seen to nest at Fertőújlak, on the Hungarian side, between 1991 and 1996, on an island covered with a weed association (HADARICS et al. 1991a and 1993b; BANKOVICS et al. 2002). On May 2, 1993, a yellow-legged gull was seen to take a fledgling from the unguarded nest of a greylag goose (Anser anser

— PELLINGER 1994). If the species takes to breeding regularly in this country, it is likely to become a threat to other bird species nesting in alkaline lakes and marshes. In the Austrian Seewinkel, it obtains its food from smaller alkaline ponds and surrounding farmland (GLUTZ and BAUER 1982). The kittiwake (Rissa tridactyla) used to be a rare visitor to Fertő (BREUER 1950b), but nowadays it is observed every year, especially on fishponds (HADARICS 1998a; MME NOMENCLATOR BIZOTTSÁG 1998b). The Caspian tern (Sterna caspia) was first recorded in Hungary in 1804 and not observed again until 85 years later. There were only five records in Hungary up to 1937. In the early 1950s, it began to be seen on alkaline lakes round Fertő, near Sankt Andrä am Zicksee (Mosonszentandrás) and Illmitz (Illmic

—BERETZK 1954). Since then, records in Hungary have proliferated (BERETZK and KEVE 1971; HADARICS 1998C). Several birds pass over Fertő regularly in the spring and autumn. In the early years of the habitatreconstruction work at Mekszikópuszta in the Fertő-Hanság National Park that began in mid1989 (KÁRPÁTI 1987d, 1988b, 1991b and 1993; PELLINGER 2001b), a small colony of common tern (Sterna hirundo) established itself on the easternmost island of Nyéki-szállás. There, 27 pairs bred in the summer of 1990, but the number fell to six by 1992, due to wave damage to the shoreline and rapid enclosure by reeds (MOGYORÓSI 1992). Several artificial islands were made using various techniques and breeding pairs returned to these in subsequent years (PELLINGER and MOGYORÓSI 1994). In 1990, six pairs of black tern (Chlidonias niger) also bred on the very edge of the black-headed gull (Larus ridibundus) colony (KÁRPÁTI 1993; PELLINGER 1995b). Earlier records of breeding by