LAUSR

The study aims to evaluate changes in occurrence of the Mandarin Duck, Aix galericulata (Linnaeus, 1758) in the Czech Republic in 2008–2019 with focus on winter months (December, January and February) 2007/08–2018/19. Seasonal dynamics of occurrence was evaluated for years 2008–2019 by comparison of 3831 observations. The highest number of observations comes from winter period (36.7%), if we exclude data from South Moravian Region (with whole year occurrence), it is 48%. In winters 2007/08–2018/19 occurrence of 772 birds was detected, most of them with determined gender – 469 males (63.4%) and 271 females (36.6%). In winter periods 2007/08–2010/11 the occurrence was concentrated in the Central Bohemian Region (Vltava river). Since the winter 2011/12 the centre of occurrence was in the South Moravian Region which is related with a formation of stable breeding population in that region. Pattern of the highest number of observations in a winter period lasts but the highest numbers of observed birds are possibly of the Czech origin.