The intensity and extensity of infestation of cormorants (Phalacocorax carbo sinensis) from a colony in Lake Selment Wielki with the tapeworm Paradilepis scolecina (Rudolphi, 1819) was examined. The cormorants were shot in April, August and October 2006 and in August and September 2007. The extensity of infection in all the cormorants under study was very high — even reaching 100 %. The highest intensity of infestation was found in the birds shot in August — 4697 tapeworms per bird in 2006 and

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... 562 in 2007. The intensity of infestation in the birds which were shot in autumn was less than one-tenth of that found in the birds shot in summer. The lowest intensity of infestation was found in the spring of 2006 — 61 tapeworms per bird.