'Sailed Eider', 3.11.2012, off Vesterø, Læsø

On November 3, 2012 I found another ‘Sailed Eider’ in Denmark. This is my third individual this year alone indicating that they are more regular than the number of records suggest. Whether they are true Northern 'borealis' Eiders or they represent intergrades between borealis and mollissima is yet undetermined. However, the characteristics of the Danish individuals are replicated within true borealis populations in the north Atlantic such as West Greenland, Northern Iceland (or are they hybrid populations?) and wintering Eiders at Svalbard.

Besides the white scapular sails several other characters indicate some degree of borealis influence, such as the head which had a high and steep forehead; the feathered white area on the side of the bill which was pointed and the black feathering below the frontal bill lobes which was very narrow; the frontal lobes on the forehead which were rather pointed and brightly coloured; and finally the white tertials which were very long and even obviously hanging down over the white rump patch.
   

According to the literature, the key features of adult male Northern Eider in relation to European Eider are:

• Two stiffer modified long scapulars creates presence of white sails on the back
• Colour on the bill base, many have orange tones over the bill base
• Legs and feet colour match the bright yellowish orange tones of the bill base
• The feathered black stripe running down the side of the bill lobe is very narrow
• The feathered white area on the side of the bill is more pointed and lack the rounded tip
• The feathered white area on the side of the bill ends below the rear edge of the nostril
• The lobes differ in shape being more pointed
• Bill shape differ structurally tending to be more elongated and drooping towards tip
• Black cap often has a straight lower edge
• Head shape tend to be squarer with steeper forehead
• Breast can be richer, deeper salmon colour
• White tertials are were very long and obviously hanging down over the white rump patch

However, one has to acknowledge that between borealis and mollissima there is a high degree of variation and overlap in these characters; thus most characters are not to be considered diagnostic, but only indicative.

Head shape was rather squarer with steep forehead

The feathered black stripe running down the side of the bill lobe was very narrow

The feathered white area on the side of the bill was rather pointed and seemed to end below the rear edge of the nostril

Note the slightly orange tones over the bill base