The Stocks of Waterbirds on the Alte Donau in Vienna

Abstract

The whole area of the River Danube in Vienna, with its three more or less parallel river stretches Donau, Neue Donau and Alte Donau is an important hibernating area for waterbirds. The “Alte Donau” is an intensely used recreation area. Here especially, people take an interest in birds and feed them in winter. For the inhabitants of a city, this close contact with birds has a highly social aspect, notably for children and elderly people. Nevertheless, the high number of birds has a negative impact on water quality. In the years 1997/1998 to 2000/2001 a total of 391.313 individuals were observed in the Viennese Danube area, consisting of 44 species of water birds, 6 gulls and 8 hybrid species. Most frequent during the whole investigation was the Black-Headed Gull (Larus ridibundus) with a maximum of 15.579 individuals on a single day; Mallard (Anas platyrhynchos) and Eurasian Coot (Fulica atra) dominate among the waterbirds (not counting gulls). Out of these 44 species 23 species of waterbirds, 3 gulls and one hybrid species and a total of 71.913 individuals were observed on the waterbody of the Alte Donau by regular countings during the winters from 1997/1998 to 2000/2001. The three most frequent species on the Alte Donau were the Black-headed Gull with a maximum of 5.965 individuals on a single day, followed by the Mallard and the Mute Swan.