Results of the January 2017 waterbird census in Slovenia

Summary In 2017, the International Waterbird Census (IWC) was carried out in Slovenia on January 14 and 15. Waterbirds were counted on all larger rivers, along the entire Slovenian Coastland and on most of the major standing waters in the country. During the census, in which 235 observers took part, 413 sections of the rivers and coastal sea with a total length of 1,427 km and 200 other localities (164 standing waters and 36 streams) were surveyed. The census was characterized by harsh winter conditions and high proportion of frozen water bodies. Altogether, 51,790 waterbirds of 61 species were counted. Thus, the number of waterbirds and the number of species recorded were close to the 21-year average. The highest numbers of waterbirds were counted in the Drava count area, i.e. 20,064 individuals (38.7% of all waterbirds in Slovenia). By far the most numerous species was Mallard Anas platyrhynchos (46.1% of all waterbirds), followed by Coot Fulica atra (6.8% of all waterbirds), Cormorant Phalacrocorax carbo (5.9% of all waterbirds), Black-headed Gull Chroicocephalus ridibundus (5.7% of all waterbirds) and Mute Swan Cygnus olor (3.9% of all waterbirds). The number of 1,000 counted individuals was also surpassed by Yellow-legged Gull Larus michahellis, Teal An. crecca, Tufted Duck Aythya fuligula, White-fronted Goose Anser albifrons, Pygmy Cormorant P. pygmeus and Grey Heron Ardea cinerea. Among the rarer recorded species, the Red-breasted Goose Branta ruficollis (registered for the first time during the January Waterbird Censuses and only for the third time ever in Slovenia) and Barnacle Goose Branta leucopsis (the first probable A category individual for IWC and Slovenia) deserve special mention. Numbers of the following species were the highest so far recorded during the IWC: Mandarin Duck Aix galericulata (together with 2006 and 2012), Pintail An. acuta, Ferruginous Duck Ay. nyroca, Long-tailed Duck Clangula hyemalis (together with 2003), Goosander Mergus merganser, Pygmy Cormorant, Herring Gull L. argentatus and Caspian Gull L. cachinnans. Number of Pochards Ay. ferina was the lowest so far recorded during the IWC.