Interspecific nest parasitism in diving ducks - Common Pochard Aythya ferina and Tufted Duck Aythya fuligula and its effect on reproductive performnce

This PhD thesis is connecting three publications and one manuscript and focuses on the study of interspecific nest parasitism among particular duck species of family Anatidae. The first part describes the occurrence of interspecific nest parasitism, in the study area of Trebon between years 1999 and 2008 in three diving duck species (Aythini): the Common pochard (Aythya ferina), the Tufted duck (Aythya fuligula) and the Red-crested Pochard (Netta rufina) and two dabbling duck species the Gadwall (Anas strepera and the mallard (Anas platyrhynchos). The most of parasitic eggs was laid by Red-creasted Pochard and Common Pochard. In this period, inter-specific nest parasitism was recorded in 6.6% of nests. The values were compared with the results of studies in the same species between 1975 and 1980. when inter-specific nest parasitism was in 13.9% of nests. The difference in rate of nest parasitism is caused as a result of a decline in breeding populations of the studied species. In the second analysis, we investigate whether parasitically laid eggs are of different size than non-parasitic eggs in three diving duck species; the Common Pochards, the Tufted Ducks and the Red-Crested Pochards. Parasitic eggs of the Common Pochard were significantly longer than non-parasitic eggs of the same species and..