Nematode communities of the gastrointestinal tract in three species of wild ducks: mallard (Anas platyrhynchos), tufted duck (Aythya fuligula) and common scoter (Melanitta nigra), from the area of Western Pomerania in Poland, were compared. Nematodes were the most numerous group in the helminth fauna of the common scoter, the second most abundant group in the mallard and the least numerous group among parasites found in the tufted duck. A total of 5348 nematodes belonging to 14 species were isolated from 366 examined ducks. Six nematode species (represented by 607 individuals) were found in mallard, 5 species (493 individuals) in tufted duck and 7 species (3576 individuals) in common scoter. Nematofauna of tufted duck was characterized by the highest species evenness, while the nematofauna of common scoter presented the greatest species diversity. The analysis of fauna similarity showed one common parasitic species (Epomidiostomum uncinatum) for mallard and common scoter, and three species (Tetrameres ryjikovi, T. spinosa and Echinuria hypognatha) for tufted duck and common scoter. Regarding the spatial distribution of nematodes most of them primarily reside in the proventriculus (84% of all nematodes in mallard and 40% in tufted duck) and gizzard (56.6% of all nematodes in tufted duck and 74% in common scoter), whereas, only individuals of the species Eucoleus contortus and Capillaria anatis were located in the oesophagus and intestine.

The results confirm that the phylogenetic differences of the three duck species, as well as the differences in their ecology are accompanied by differences in the structure of parasitic nematode community.