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

Abstract

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.