December 28th 2006. Macmillan Wharf, Provincetown Harbor, MA. Probable 'Northern' Eider. Somateria mollissima (borealis). Adult male. (All the shots refer to the same adult male taken in a variety of lighting conditions). This striking Eider caught my attention straight away as I was attempting to digiscope the Thayer's Gull present at the same site. The orange base to the bill wasn't always that obvious against the light, but really jumped out at other times. Most striking of all was the shape of the frontal bill lobes which tapered almost to a point. The head shape was also rather distinct when seen in direct comparison to several adult male S.m. dresseri, with the suspected borealis showing a much steeper forehead and flatter crown. This created a square-headed impression evident in most of the images below. NB. Borealis is apparently very rare in MA with only three records listed in the 'Birds of Massachusetts' by Veit and Petersen, the last one being in 1946! Update: Captioned images of S.m. borealis and S.m. dresseri added on January 1st, 2007. A very useful reference on the different forms of Common Eider by Martin Garner and Wilton Farrelly. Images taken using Canon Powershot A540 through Swarovski HD Telescope. |
 Suspected 'Northern' Eider. Somateria mollissima (borealis). Adult male.  'American' Eider. Somateria mollissima (dresseri). Adult male.  Comparison of head shape and frontal bill lobes between borealis (rear) and dresseri.  Beautiful comparison of head and frontal bill lobe shape between S.m. borealis (foreground) and S.m.dresseri.   The bill color varied considerably under certain lighting conditions. Compare the two shots above with the images below.   'American' Eider. Somateria mollissima (dresseri). Adult males. Nice comparison of two males of the same form showing slight variation in shape of frontal bill lobes and amount of visible black along outer edge of bill lobes. Both of these males show orange toned bills and prominent mantle 'sails'.  Suspected 'Northern' Eider. Somateria mollissima (borealis). Adult male. Provincetown Harbor. |