Početnosť zimujúcich vodných vtákov na severe Slovenska počas januárov 2014 – 2018 / The number of wintering waterbirds in northern Slovakia in Januaries 2014–2018

Abstract

The structure of wintering waterbird assemblages is highly affected by the temperature. Wintering birds are not able to find enough food during the cold winters and they have to migrate to areas with better conditions. During the Januaries 2014–2018 44 (yearly 23–34) water bird species were registered in three regions of Northern Slovakia. The overall number of wintering birds ranged from 9125 to 12,639. There was found the significant impact of the temperature on the number of diving ducks. Mainly the Common Merganser and the Common Goldeneye significantly increased their numbers in winters with lower temperature. The most prominent influence between temperature and the number of wintering birds was found in last two Januaries (2017 and 2018) which were significantly different in average temperature. January 2017 was about 8.5 °C colder than January 2018 and many wintering localities were frozen. Despite this fact the number of wintering birds in 2017 was higher than in 2018. However, the number of species has decreased in 2017. The most of the differences were caused by the changing numbers of diving ducks which had to leave traditional wintering sites in northern parts of Europe during cold winter of 2017.

Keywords

• abundance
• dominance
• aythya fuligula
• mergus merganser
• bucephala clangula