[Fleas from the nests of goosander (Mergus merganser L.)].

In 1993 43 nests of Goosander from the Jasień Lake near Bytów were collected and checked on fleas presence. Ceratophyllus gallinae, the only one fleas species, was found in 60.5% nests. Among nests where the fleas were found the most frequent were those inhibited by 1-10 specimens of fleas (12 nests). The highest mean number of fleas per nest and the highest percentage of nests with fleas were noted before the breeding season has started (in March) and the lowest after the fresh brood in May. More fleas were noted in nests with successful broods. M. merganser was not yet noted in Polish literature as a host of C. gallinae in Poland.