8 Steller’s Eider (Polysticta stelleri): vulnerability to climate change
8.1 Evidence for exposure
8.1.1 Potential changes in breeding habitat suitability:
While this species does occassionally breed in Europe, recent assessments have concluded these populations are not permanent and are generally at very low densities. As such, no habitat suitability assessment was carried out
8.2 Sensitivity
- This species has a large population, a large range, but is declining globally. In Europe the overall trend is unclear, there have been drastic declines in the Baltic, but this may be due to redistributions to other areas, in particular the north coast of Russia. Any existing declines are likely to be exacerbated by climate change.
- Eiders have shown declines during historical regime shifts in marine ecosystems, they are likely to be sensitive to future changes in marine ecosystems.
- Eiders are vulnerable to predation by foxes and other mammals. Other eider species have suffered increased predation as a result of climate change. While this has not been observed in Steller’s eiders, any increase in predation could have significant impacts on populations
- Many of the species’ key life-history traits are unknown. Many impacts to the population are unlikely to be detected quickly, and conservation action is likely to be challenging
- Eiders form large rafts especially in the non-breeding season, making them particularly vulnerable to mass mortality events. Even localised climate change impacts may have large consequences on the population as a whole.
- Key wetland breeding habitats across the Arctic are rapidly disappearing or changing. The overall impact on eider populations is unknown, but very likely to be negative.
- Eiders have a varied diet of invertebrates but many populations are strongly reliant on Mytilus and other gastropods for much of the year. Mytilus and other gastropods are known to be sensitive to climate change, and warmer conditions is likely to result in reductions of key prey species. In addition, eiders show a preference for foraging in kelp beds, and any impacts to these may have severe negative consequences for foraging eiders.
8.3 Adaptive capacity
- While the species is generally considered to have high site fidelity to moulting and wintering sites, the species has demonstrated range shifts in response to climate change. Large numbers have redistributed to northern Russia as sea ice has decreased over recent decades.
- Eiders either abandon or skip breeding in particularly unsuitable years, preserving resources. This could be adaptive if conditions become more variable and ameliorate the impact of poor breeding conditions