Climate‐driven changes in winter abundance of a migratory waterbird in relation to EU protected areas

Abstract

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.

Long-term trends, total numbers and species richness of increasing waterbird populations at sites on the edge of their winter range: cold-weather refuge sites are more important than protected sites

“…As a consequence, changes in species distributions could lead to increases in species richness and numbers in locations at the edge of what might have been previously considered to be 'normal' wintering areas Pavón-Jordán et al 2015).…”

“…Despite both increasing and decreasing trends in wintering waterbird population sizes in the Western Palearctic (Wetlands International 2006, previous studies have consistently shown a prevailing increase in the numbers of most waterbird species in Central Europe (Fox et al 2010;Keller 2011;Musil et al 2011;Slabeyová et al 2014), most likely due to the results of large-scale changes in the climate (Ridgill and Fox 1990;Maclean et al 2008;Lehikoinen et al 2013;Pavón-Jordán et al 2015). Moreover, the higher levels of eutrophication of European wetlands in the 20th century (Vollenweider 1968) may have led to increases in the trophic levels of wetlands and, consequently, increases in wintering waterbird numbers, as has been shown in Switzerland (Suter and Schifferli 1988).…”

“…As was shown in a previous study (Musil et al 2011), among the speciesspecific variables affecting trends in individual species, the overall trend in the Western Palearctic is the most important factor affecting local trends in the numbers and distribution of a particular species; almost all our study species follow the respective overall trends in the Western Palearctic. Moreover, recently published flyway-level studies of individual species indicate changes in wintering distribution Pavón-Jordán et al 2015). The question then arises: Are we able to assess the importance of sites using site-specific conditions, when the long-term changes in distribution and numbers of waterbirds are likely to be more influenced by macroscale effects at the flyway level?…”

“…It may also be expected that regional and local factors would affect these parameters at any given site. However, distributional shifts in wintering ranges may result in the current network of protected areas gradually losing its relevance (Guillemain et al 2013), with new wintering sites, as well as even non-protected areas, becoming the more important sites for numerous wintering waterbirds (see, for example, Rodrigues et al 2004;Pavón-Jordán et al 2015). The wintering distributional changes of individual species due to recent climate change could lead to a northwards shift of wintering areas in the Western Palearctic (reviewed by Guillemain et al 2013; see also Lehikoinen et al 2013) and may affect species richness and numbers at the site level.…”

“…Given the observed climate-driven shifts of wintering distributions (Ridgill and Fox 1990;Rehfish et al 2004;Austin and Rehfish 2005;Rainio et al 2006;Lehikoinen et al 2013), we consider the effect of a site's geographical position, as well as its nature protection status (protected site or not). We suppose that even non-protected areas could represent important sites for increasing numbers of wintering waterbirds (see, for example, Rodrigues et al 2004;Pavón-Jordán et al 2015) as the distribution of a species can be very dynamic (e.g. Walther et al 2002;Maclean et al 2008;Lehikoinen et al 2013) and, in contrast, the status of protected areas can be static over time.…”