Steller's Eiders Polysticta Stelleri Research Articles

Climate change and coastal wetland salinization: Physiological and ecological consequences for Arctic waterfowl

Abstract Coastal wetland salinization related to warming climate has the potential to impact ecological systems globally. In Alaska, the Yukon‐Kuskokwim Delta (YKD) supports large concentrations of breeding water birds and is an ecologically important area for conservation of migratory bird biodiversity. On the YKD, the majority of waterfowl nest in low elevation coastal tundra where storm surges drive saline water into terrestrial wetland habitats. Because newly hatched water birds lack functional salt glands to process saline water, salinization may negatively impact their growth and survival. We investigated potential demographic impacts of wetland salinization by conducting controlled physiological experiments to determine consequences of saline water exposure to spectacled Somateria fischeri and Steller's eider Polysticta stelleri ducklings, and analysed habitat suitability based on experimentally defined tolerance thresholds and sampled wetland salinity levels. We found physiological and behavioural pathologies in <1 week old ducklings at exposure levels of 6 parts per thousand (ppt), and found some evidence of reduced growth in ducklings first exposed after 1 week of age. We conclude that the acute toxicity threshold for ducklings <1 week of age is ≤6 ppt. We found that the area of coastal tundra where wetland salinity exceeded 6 ppt varied considerably among years, suggesting that some portion of the breeding range is unsuitable for rearing ducklings in some years. However, we also found that most eiders in most years nested in areas with salinity at or exceeding the tolerance threshold for ducklings, suggesting that nesting eiders do not appear to avoid saline habitats. We suggest that localized fresh water refugia currently may allow resilience to salinization during the critical period. Understanding how species and habitats respond to climate driven changes is essential for predicting future patterns of distribution and abundance, and is necessary for making informed decisions about conservation priorities. Our study provides insights into the extent of wetland salinization in Alaska, mechanism of impact and current ecological consequences on avian communities depending on these habitats. With ongoing climate change, the probability of species crossing physiological tolerance thresholds of wetland salinity may change in the future. Read the free Plain Language Summary for this article on the Journal blog.

Recent changes in the status of Steller's Eider Polysticta stelleri wintering in Europe: a decline or redistribution?

Steller's Eider Polysticta stelleri has a restricted arctic breeding range. The world population declined to c. 220,000 individuals in the late 1990s from an estimated 400,000–500,000 in the 1960s. The species has a limited global wintering distribution, occurring in marine habitats in north-east Europe, islands close to Kamchatka in Russia, and the eastern Aleutian Islands and south-west Alaska. European wintering numbers were estimated at 30,000–50,000 in the early 1990s, when the population was considered of favourable conservation status. Recent census data from the most important European wintering sites show annual declines of 8% in Norway since 1984, 9% in Estonia since 1994 and 22% in Lithuania since 1995, suggesting an overall 65% reduction in Europe. Counts in 1994 suggested that 30–50% of the European population wintered in Russia at that time. Current census data from Russia show similar declines along monitored sections of the Kola Peninsula wintering grounds since 1994. Accounting for trends in Russia, the current European wintering population could possibly stand at 10,000–15,000 individuals (a more than a 50% decline in 10 years), qualifying this population as Endangered under IUCN criteria. The changes in Baltic/Norwegian wintering numbers did not correlate with changes in the extent of ice-free marine waters in the Kola Peninsula/White Sea areas, but changes in annual numbers in Norway were correlated with winter North Atlantic Oscillation indices. Variation in annual numbers in the Baltic Sea correlated with projected number of juveniles among wintering birds. However, none of the possible causes discussed in this paper could fully explain the decline in Steller's Eider, confirming the need for comprehensive monitoring of the population throughout its winter range and for cohesive demographic monitoring to target effective conservation action.

Breeding and moulting locations and migration patterns of the Atlantic population of Steller's eiders Polysticta stelleri as determined from satellite telemetry

This study was designed to determine the spring, summer, autumn, and early winter distribution, migration routes, and timing of migration of the Atlantic population of Steller's eiders Polysticta stelleri. Satellite transmitters were implanted in 20 eiders captured in April 2001 at Vadsø, Norway, and their locations were determined from 5 May 2001 to 6 February 2002. Regions where birds concentrated from spring until returning to wintering areas included coastal waters from western Finnmark, Norway, to the eastern Taymyr Peninsula, Russia. Novaya Zemlya, Russia, particularly the Mollera Bay region, was used extensively during spring staging, moult, and autumn staging; regions of the Kola, Kanin, and Gydanskiy peninsulas, Russia, were used extensively during spring and moult migrations. Steller's eiders migrated across the Barents and Kara seas and along the Kara Sea and Kola Peninsula coastal waters to nesting, moulting, and wintering areas. The majority of marked eiders (9 of 15) were flightless in near‐shore waters along the west side of Novaya Zemlya. Eiders were also flightless in northern Norway and along the Kanin and at Kola Peninsula coasts. We compare and contrast natural history characteristics of the Atlantic and Pacific populations and discuss evolutionary and ecological factors influencing their distribution.

Breeding and moulting locations and migration patterns of the Atlantic population of Steller's eiders Polysticta stelleri as determined from satellite telemetry

Breeding and moulting locations and migration patterns of the Atlantic population of Steller's eiders Polysticta stelleri as determined from satellite telemetry

Spring habitat use and feeding behaviour of Steller's Eider Polysticta stelleri in Varangerfjord, northern Norway

The distribution and abundance of Steller's Eider Polysticta stelleri were studied in Varangerfjord, Norway, in May 1995, immediately prior to the birds' departure for the breeding areas. Almost 80% of the variance in Steller's Eider numbers was explained by a regression model based upon low tide beach width, suggesting strong selection for gently shelving coastal profiles. Such habitat is common but restricted in Varangerfjord and is rare along surrounding coastlines where the species is more scarce. The majority of Steller's Eider and the Common Eider Somateria mollissima were recorded within 200 m of the coast, in contrast to the King Eider Somateria spectabilis, which tended to be more than 200 m from the shore. More detailed observations at one study site showed that Common and Steller's Eiders fed in different ways and in separate areas, despite similar proximity to the shore, although the two species did aggregate together to roost at high tide, particularly during the daytime. Steller's Eider showed a strong tidal rhythm in activity by day and night, roosting at high tide, diving offshore on the ebb and flow tides but resorting to algal beds and sandy‐mud beaches to feed at low tide.

Rafting behaviour and predator disturbance to Steller's EidersPolysticta stelleri in northern Norway

Steller's Eiders responded to overflying Great Black-backed GullsLarus marinus by “spooking” — flushing from feeding and aggregating on open water. Birds did not react at high tide when aggregated into dense roosting flocks. The significant reduction in inter-bird distance associated with this escape behaviour suggests that rafting in this way (and at rest) serves an anti-predator function. In 32% of spooks, up to 56% of the flocks were displaced from feeding sites; even when all birds remained, they took an average of 3.5 minutes for half of the flock to resume feeding, representing a minimum total of 17% loss of feeding time throughout the 24 hour period. At observed rates, the cost of flight behaviour in response to gulls was estimated to equate to a minimum of 7.8% of daily existence energy. Hence such predator responses can cost Steller's Eiders loss of access to favoured feeding area, loss of feeding time (already restricted by tidal exposure) and additional energy costs.