Climate change is predicted to cause changes in species distributions and several studies report margin range shifts in some species. However, the reported changes rarely concern a species' entire distribution and are not always linked to climate change. Here, we demonstrate strong north-eastwards shifts in the centres of gravity of the entire wintering range of three common waterbird species along the North-West Europe flyway during the past three decades. These shifts correlate with an increase of 3.8 °C in early winter temperature in the north-eastern part of the wintering areas, where bird abundance increased exponentially, corresponding with decreases in abundance at the south-western margin of the wintering ranges. This confirms the need to re-evaluate conservation site safeguard networks and associated biodiversity monitoring along the flyway, as new important wintering areas are established further north and east, and highlights the general urgency of conservation planning in a changing world. Range shifts in wintering waterbirds may also affect hunting pressure, which may alter bag sizes and lead to population-level consequences.

Because population size is sensitive to changes in adult survival, adult survival may be buffered against environmental variability. Philopatry may be adaptive in changing environments, but it could also constrain breeding habitat selection under changing conditions such as shifting predation regimes. Habitat preference and quality could become decoupled in long-lived philopatric species that evolved in stable environments when suddenly faced by increased adult predation risk, as dispersal may be triggered by past reproductive failure. We evaluated whether the Baltic eider (Somateria m. mollissima) population may currently face a predation-induced ecological trap. Eiders are philopatric and nest on open and forested islands. We hypothesized that open-nesting females would be disproportionately affected by increased predation. We compared female annual survival in these two habitats in 1996-2010. We also tested for effects of time trends, winter severity (NAO), female body condition, and habitat-specific predation pressure on survival. Our results revealed the lowest survival recorded for this species (Φ = 0.720), and survival on open islands was significantly lower (Φ = 0.679) than on forested islands (Φ = 0.761). Nonetheless, only 0.7 % of females changed breeding habitat type despite ample availability of alternative islands, and breeding phenology in both habitats was similar. Female survival increased with body condition, while it was unrelated to winter climate and stable over time. Open islands had a higher predation pressure on incubating females. Breeding philopatry results in a predator-mediated ecological trap for open-nesting eiders. Our results contribute to explaining the drastic decline of the Baltic eider population.

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