Update, December 01, 2014: added another Scottish eider that has features of borealis and seems to have at least one "sail" - at bottom of Scottish eider entry:
Update, November 11, 2014: added comparison photos of two rather different dresseri from Massachusetts - at the bottom of the page:
These
Common Eiders Somateria mollissima were along the coast at Peterhead, NE Scotland in late February 2009; they demonstrate a bewildering range of variation in the shape and colour of the frontal processes on the bill. On range these should all be S. m. mollissima, yet these three individuals variously look like the arctic form S. m. borealis - but none showed any sign of scapular "sails". Not all presumed borealis-types from Iceland show the scapular "sails" CLICK HERE TO SEE ONE. :-
A) This bird had a strikingly orange bill and stood out even from the more ochre-billed individuals among the flock of nominate birds:
This individual (very bottom of the photo) has an ochre-colored bill (okay for nominate and some populations of borealis) but with the processes ending in a broad lobed shape approaching that seen on western Atlantic S. m. dresseri(and some Icelandic birds currently classified as borealis but which show possible signs of introgression from dresseri-types?) :
This last one really does look like some of the Icelandic birds that show signs of dresseri-type lobes - compare it to these borealis-type birds from Iceland HERE and HERE :
Update, December 01, 2014: Another Scottish eider from the same location/timeframe as the birds above; it has features of borealis and seems to have at least one "sail" -
The location of the "sail" is precisely where they appear on borealis-type males in Iceland - CLICK HERE TO SEE ONE:
Update, November 11, 2014: these two somewhat different dresseri are from Glaucester harbor, Massachusetts; note the prominence of the "sails":
