Fish farms as nesting sites for Chlidonias hybridus (Aves, Charadriiformes, Sternidae)

Since 1948 the Prut River basin has been subject to high levels of hydrotechnical and hydrological works. As a result of these many aquaculture ponds for rearing fish have appeared. These aquatic basins represent concentration areas of some important populations of bird species, both during migration and reproduction. The avifauna of the lower basin of River Prut was relatively un-studied until 1992. Since then numerous studies were conducted on the dynamics of the bird populations (including Chlidonias hybridus) in the Romanian basin of River Prut. In this study I detail the size of the breeding populations of Chlidonias hybridus species in the fish-ponds of the lower basin of River Prut and their change beteen 2002 and 2005. The study was conducted between May and July (2003-2005). C. hybridus colonies were surveyed within the Carja-Ma a-R deanu ponds, Vl de ti ponds and Brate fishponds complex, located in the Prut river lower basin. The results observed are discussed with respect to the weather conditions that determine the nesting of this species in the fish-ponds, the influence of the fishery works on the C. hybridus colonies and the importance of the ponds as nesting places for this species.