Seasonal dynamics and winter occurrence of non-native species - Mandarin duck (Aix galericulata) in the Czech Republic.
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.