Morphometrical and ecological analysis of nematodes of the family Capillariidae (Neveu-Lemaire, 1936) in wild ducks (Anatinae) from the north-western Poland.

West Pomerania is located on the migratory route of many species of birds. Among them are many representatives of wild duck species (subfamily Anatinae), which are often the primary hosts of many helminths due to the fact of living in two different environments: terrestrial and aquatic. However, until the end of the 90s, research conducted in Poland on the helminth fauna of wild birds, including nematodes of the family Capillariidae, did not include the north-western region of the country. These first studies performed in 1999, aimed at the identification of the nematodes of wild ducks from the West Pomerania region, revealed the presence of three species belonging to family Capillariidae, i.e. Capillaria anatis (Schrank, 1790) Travassos, 1915, Eucoleus contortus (Creplin, 1839) Gagarin, 1951 and Pseudocapillaria mergi (Madsen, 1945). The purpose of the current study was to perform a comprehensive ecological analysis of C. anatis, E. contortus and P. mergi, including such factors as intensity, prevalence, relative density, index of fidelity and dominance index. The experimental material comprised 811 nematodes isolated from the gastrointestinal tracts of 953 ducks. These 9 species of ducks belong to three different tribes of the Anatinae subfamily: Anatini (Anas clypeata, A. crecca, A. platyrhynchos), Aythyini (Aythya fuligula, A. marila) and Mergini (Bucephala clangula, Clangula hyemalis, Mergus merganseri, Somateria mollissima) and diverse in terms of their biology and ecology. The morphometric and morphological analyses fail to identify any significant differences in the body structures of nematodes of the species C. anatis, E. contortus and P. mergi of the West Pomerania region in comparison with those found in other regions of Poland and Europe. The ecological analysis of the Capillariidae family in the West Pomerania region revealed that ducks of the tribe Anatini (mainly A. platyrhynchos) are the most common hosts of E. contortus species, C. anatis is most commonly found in ducks of the tribe Aythyini, and P. mergi is relatively frequent in ducks of the tribe Mergini (mainly in M. merganser).