Changes in numbers and distribution of wintering waterbirds around Gotland 1969–2020

Abstract

The coastal areas of the island of Gotland in the center of the Baltic Sea is an important wintering site for waterbirds in Sweden. Gotland offers extensive areas of shallow feeding grounds and, due to its location, some open waters remain available even during harsh winters. Wintering waterbirds have been counted annually on the island since the start of the International Waterbird Census in 1967, with full coverage of all the inshore areas around the main island obtained during the years 1969–1978 and 2013–2020. Between these two periods, the mean total number of wintering waterbirds increased from 32,000 to 111,500. The most numerous species were Mallard Anas platyrhynchos, Tufted Duck Aythya fuligula, and Common Goldeneye Bucephala clangula. Some species such as Eurasian Wigeon Mareca penelope, Eurasian Teal Anas crecca, and Gadwall Mareca strepera started to winter during the second period. Marked increases were also found for Smew Mergellus albellus and Greater Scaup Aythya marila, likely related to progressively milder winters in recent years.

Evaluation of different wetland preferences of wintering waterbird species in Çanakkale, Turkey

“…With the global climate change, bird species can spend the winter months in more northern latitudes with milder weather conditions. In a study conducted by Nilsson & Hermansson (2021) on Gotland Island (Sweden) in the Baltic Sea, in IWC censuses between 1969-1978-2020, the average total number of waterbirds overwintering between the two periods increased from 32,000 to 111,500, and the observed increase stated that it may be associated with increasingly mild winters in recent years (Nilsson & Hermansson, 2021). Despite being one of the most important biodiversity hotspots in the world, increased monitoring efforts for waterbirds are needed, especially in the southern half of the Mediterranean Basin (Galewski et al, 2011).…”

“…But there are studies evaluating IWC counts conducted in important wetlands in Turkey and around the world and the anthropogenic factors on the areas. (Yarar et al, 1996;Yavuz & Boyla 2013;Çağlayan et al, 2005;Suseven et al, 2006;Onmuş, 2007;Arslangündoğdu, 2009;Akarsu & Balkız, 2010;Erciyas Yavuz & Kartal, 2012;Özkoç et al, 2019;Nilsson, 2020;Ulusoy & Bulut, 2020;Nilsson & Hermansson, 2021). In the two-year IWC census, 26975 individuals from 14 species and 13158 individuals from 19 species were counted, respectively, in the Obruk Dam Lake, which has a surface area of 5021 hectares (Ulusoy & Bulut, 2020).…”

Clas Hermansson in memoriam

“…CL A S HERMANSSON is one of the co-authors of a paper in this volume of Ornis Svecica (Nilsson & Hermansson 2021), one of many articles that he has written in different ornithological journals over the years. However, as the first Common Cranes Grus grus arrived at Lake Hornborgasjön this spring on their migratory journey back from their winter quarters, the sad news reached us: Clas Hermansson had passed away at the age of 73 after a period of illness.…”