| Summary: | During the years 2003-2010, the numbers of pairs of waterbird species breeding in the city of Wrocław (293 km2) were assessed. The city is situated in Odra valley, where four smaller rivers join it. The city abandons in oxbows, gravel and sand, and clay pits and other water bodies. In total, 20 waterbird species were recorded as breeding in Wrocław. The most common were Anas platyrhynchos (145-212 pairs), and Fulica atra (70-104 pairs). Relatively common were also the Gallinula chloropus (28-37 pairs), Rallus aquaticus (9-25 pairs) and Cygnus olor (9-11 pairs). For each remaining species less than 10 pairs were recorded. Among rare species, the following were recorded as breeding in Wrocław: Grus grus, Mergus merganser, and Porzana porzana. In the few recent decades, the increase in the number of breeding pairs was recorded for Anas platyrhynchos and Cygnus olor; while a parallel decrease was recorded for Fulica atra, Gallunula chloropus, Chroicocephalus ridibudnus, and Tachybaptus ruficollis. Species such as the Aythya fuligula, Aythya ferrina, grebes, gulls and terns avoid the city. Some of them even ceased to breed (Anas quarquedula, Anas clypeata and Botaurus stellaris). The city plays an important role in protecting water bird species such as Grus grus, Cygnus olor, Porzana porzana and Alcedo atthis.
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