Changes in habitat suitability influence non‐breeding distribution of waterbirds in central Europe

Abstract

Waterbird species have different requirements with respect to their non-breeding areas, aiming to survive and gain condition during the non-breeding period. Selection of nonbreeding areas could change over time and space driven by climate change and species habitat requirements. To help explain the mechanism shaping non-breeding area selection, we provide site-specific analyses of distributional changes in wintering waterbirds in central Europe, located at the centre of their flyways. We use wintering waterbirds as a highly dynamic model group monitored over a long-time scale of 50 years . We identified species habitat requirements and changes in habitat use at the level of 733 individual non-breeding (specifically wintering) sites for 12 waterbird species using citizen-science monitoring data. We calculated site-specific mean numbers and estimated site-specific trends in numbers. The site-specific approach revealed a general effect of mean winter temperature of site (seven of 12 species), wetland type (all species) and land cover (all species) on site-specific numbers. We found increasing site-specific trends in numbers in the northern and/or eastern part of the study area (Mute Swan Cygnus olor, Eurasian Teal Anas crecca, Common Pochard Aythya ferina, Great Cormorant Phalacrocorax carbo and Eurasian Coot Fulica atra). Common Merganser Mergus merganser, Great Cormorant, Grey Heron Ardea cinerea, Common Pochard, Eurasian Coot and Common Moorhen Galinulla chloropus increased their site-specific numbers on standing industrial waters with traditionally low fish stock. The site-specific dynamics of bird numbers helped us to identify general preference for sites reducing winter harshness (warmer areas, running waters and more wetlands in the site vicinity), as well as indicating climate-driven changes in spatial use of wintering sites (northern/north-eastern range changes and changes in preference for industrial waters). This fine-scale (site-specific) approach can reveal large-scale range and distribution shifts driven by climate and environmental changes regardless of the availability of large-scale datasets.

Habitat‐ and species‐mediated short‐ and long‐term distributional changes in waterbird abundance linked to variation in European winter weather

“…Shallow‐water species typically have more northern and eastern breeding distributions (which are not suitable for waterbirds during winter) compared to deep‐water species (Wernham et al., ). Many deep‐water species, in contrast, breed in central Europe, where relatively modest amelioration in winter weather conditions (increasing NAO) can enable suitable wintering habitat to persist, allowing deep‐water species to winter closer to their breeding grounds (Musilová, Musil, Zouhar, & Adam, ). However, further increases in NAO make little further difference to habitat availability and hence do not contribute to further distributional shifts to the north and east.…”

Changes in wetland habitat use by waterbirds wintering in Czechia are related to diet and distribution changes

“…On the species level, prevailing decreasing or stable trends in abundances were found in running waters, which represent the traditional wintering grounds in the study region (Adam et al, 2015;Musilová et al, 2015Musilová et al, , 2018a. It is worth noting that running waters fulfil one of the most important habitat requirements for wintering waterbirds: to avoid unfavourable winter harshness and destructive winter extremes in the zero-degreeisotherm area (Musilová et al, 2015(Musilová et al, , 2018a. In recent decades, milder winter conditions in Central Europe (IPCC, 2014) probably provide an increased availability of new wintering areas, i.e.…”

“…The non‐breeding distribution and habitat use of many waterbirds have changed considerably during recent decades, with new important wintering areas being established in northern and eastern Europe (Lehikoinen et al., 2013; Nuijten et al., 2020). This phenomenon has been linked to climate‐driven range changes and redistribution of abundances (Maclean et al., 2008; Musilová et al., 2018a; Nilsson, 2008; Pavón‐Jordán et al., 2015, 2019; Thomas et al., 2012).…”

“…In addition to using newly available northern coastal areas around the Baltic Sea (Lehikoinen et al., 2013), many wintering waterbirds are progressively using inland waters in east and central Europe to a greater extent when compared to the 1990s (Musilová et al., 2018a; see also Guillemain & Hearn, 2017; Pavón‐Jordán et al., 2020). Climate warming is shifting the zero‐degree isotherm (i.e.…”

“…Climate warming is shifting the zero‐degree isotherm (i.e. average aerial temperature of 0°C in January) and thus increasing also the availability of free‐ice inland freshwater wetlands in this region (Musilová et al., 2018a; Pavón‐Jordán et al., 2015, 2019). Some species are rapidly responding to this phenomenon and increasingly using the newly available wetlands in central and east Europe by altering their migratory behaviour (Adam et al., 2015; Beekman et al., 2019; Gunnarsson et al., 2012; Podhrázský et al., 2017; Sauter et al., 2010; Švažas et al., 2001).…”