Aim Species are responding to climate change by changing their distributions, creating debate about the effectiveness of existing networks of protected areas. As a contribution to this debate, we assess whether regional winter abundances and distribution of the Smew Mergellus albellus, a migratory waterbird species listed on Annex I (EU Birds Directive) that overwinters exclusively in European wetlands, changed during 1990–2011, the role of global warming in driving distributional changes and the effectiveness of the network of Special Protection Areas (SPAs, EU Birds Directive) in the context of climate change. Location Europe. Methods We used site‐specific counts (6,883 sites) from 16 countries covering the entire flyway to estimate annual abundance indices and trends at country, region (north‐eastern, central and south‐western) and flyway scales, inside and outside SPAs. We fitted autoregressive models to assess the effect of winter temperature on the annual abundance indices whilst accounting for autocorrelation. Results The Smew wintering distribution shifted north‐eastwards in Europe in accordance with the predictions of global warming, with increasing numbers in the north‐eastern region and declines in the central region. Trends in wintering numbers were more positive in SPAs on the north‐eastern and south‐western part of the flyway. However, a large proportion of the wintering population remains unprotected in north‐eastern areas outside of the existing SPA network. Main conclusions SPAs accommodated climate‐driven abundance changes in the north‐eastern region of the wintering distribution by supporting increasing numbers of Smew in traditional and newly colonized areas. However, we highlight gaps in the current network, suggesting that urgent policy responses are needed. Given rapid changes in species distributions, we urge regular national and international assessments of the adequacy of the EU Natura 2000 network to ensure coherence in site‐safeguard networks for this and other species.

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Aim Many species are showing distribution shifts in response to environmental change. We explored (a) the effects of inter‐annual variation in winter weather conditions on non‐breeding distributional abundance of waterbirds exploiting different habitats (deep‐water, shallow water, farmland) and (b) the long‐term shift in the population centroid of these species and investigate its link to changes in weather conditions. Location Europe. Methods We fitted generalized additive mixed Models to a large‐scale, 24‐year dataset (1990–2013) describing the winter distributional abundance of 25 waterbird species. We calculated the annual and long‐term (3‐year periods) population centroid of each species and used the winter North Atlantic Oscillation (NAO) index to explain the inter‐annual and long‐term shifts in their location. Results (a) Year‐to‐year southwestwards shifts in the population centroids of deep‐ and shallow‐water species were linked to negative NAO values. Shallow‐water species shifted northeastwards associated with positive NAO values and the distance shifted increased with increasing NAO. Deep‐water species shifted northeastwards up to zero NAO indices, but showed no further increase at higher NAO values. (b) Deep‐water species showed long‐term northeastwards shifts in distributional abundance throughout the 1990s and the 2000s. Shallow‐water species, on the other hand, shifted northeastwards during the 1990s and early 2000s, but southwestwards thereafter. There were no significant links between the NAO and year‐to‐year movements or long‐term shifts in farmland species’ population centroid. Main Conclusions We provide evidence for a link between both year‐to‐year and long‐term changes in waterbird winter distributional abundances at large geographical scales to short‐ and long‐term changes in winter weather conditions. We also show that species using shallow water, deep‐water and farmland habitats responded differently, especially at high NAO values. As well as important ecological implications, these findings contribute to the development of future conservation measures for these species under current and future climate change.

Article impact statement: Protected areas are needed to facilitate waterbird distribution change in response to climate warming in the Western Palearctic.

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