CHANGES IN ABUNDANCE OF WATER BIRDS SPECIES IN SOUTHERN BOHEMIA (CZECH-REPUBLIC) IN THE LAST 10 YEARS

In 1981-1992, the breeding fauna of 153 fishponds was studies in three fishpond regions in south Bohemia (Czechoslovakia). On each pond, all water and wetland birds were censused by the Two-check method, which consists of adult birds counts during each breeding season (the first in the second part of May, and the second in the second part of June). We assessed the numbers of all species living in water and wetland ha bitats in the breeding season. The decline in abundances (expressed as number of individuals) of ducks (Anatinae), grebes (Podicipediformes) , Coot (Fulica atra), Moorhen (Galinulla chloropus), Black-headed Gull (Larus ridibundus) were the most marked changes recorded. Marked incr ease in abundances was found in Cormorant (Phalacrocorax carbo) and Mu te Swan (Cygnus olor) during the whole decade, whereas in Graylag Goos e (Anser anser) the increase was restricted to the first half of the p eriod under study. Numbers of charadriform and passeriform birds fluct uated in the dependence of water level variation.