BIRD COMMUNITIES OF THE WATER RESERVOIRS IN WESTERN SLOVAKIA

In the years 1990-1995 we carried out a bird investigation on 5 water reservoirs on the Chvojnicka pahorkatina hilly country and on 2 reserv oirs on the Borska nizina lowland. We aimed at species diversity, abun dance, dominance, frequency and coenological correspondence. The resul ts were compared with those ones of our investigations on the water re servoirs in the Male Karpaty Mts and Trnavska pahorkatina hilly countr y. On 7 investigated reservoirs we have established 50 water bird spec ies, out of this 19 ones were nidificants. Hereby the number of specie s established by us up to now and bound to water reservoirs of Western Slovakia increased to 75. The highest dominance on the reservoirs on the Chvojnicka pahorkatina hilly country and Borska nizina lowland had 7 species, the highest frequency 3 ones. The specific eudominant and at the same time euconstant species for the Chvojnicka pahorkatina hil ly country was Anas platyrhynchos. On the reservoirs of Borska nizina lowland it was Podiceps cristatus. Both species are characteristic for the biotopes of the investigated area. The comparison of ornithocoeno ses on all investigated reservoirs in four geomorphological units of w estern Slovakia (Chvojnicka pahorkatina hilly country, Borska nizina l owland, Male Karpaty Mts. Trnavska pahorkatina hilly country) showed t hat the nesting bird communities point out greater similarity than the communities of all established species. It proves that in settling of water reservoirs, as a new anthropogenous biotope, the development of water and shore vegetation has a determining role.