Wintering Rooks, Corvus frugilegus (Aves, Corvidae) and Their Helminths in Poltava and Kyiv, Ukraine

Observations of wintering rook populations were carried out from late October till early March in 2020–2021 and 2021–2022 in the cities of Poltava and Kyiv. In Poltava, rooks made up 95 % of the approximately 50,000 wintering corvids, and in Kyiv, more than 93% of the approximately 90,000 corvids. Up to 10 % of the rooks observed in Poltava were juveniles; no juvenile rooks were observed in Kyiv. Forty-six dead rooks (24 in Poltava and 22 in Kiev) collected on the ground at roosting sites were used for parasitological studies. We found 13 helminth species in the two samples of rooks, 10 species were recorded in each sample. In both samples, nematodes predominated by their infection prevalence and abundance. At the levels of helminth populations and infracommunities, the differences between the two samples were mostly influenced by the infection parameters of the nematodes Acuaria anthuris, Baruscapillaria resectum, Diplotriaena tricuspis, Eucoleus frugilegi, Microtetrameres spp., and the cestode Spiniglans affinis. In the helminth component community from Poltava, the evenness and diversity indices were comparatively higher than in the component community from Kyiv; Microtetrameres spp. was the predominat taxon. In the component community from Kyiv, E. frugilegi predominated by its infection prevalence and abundance.