Found off the east side of Gurnet Point on Thurs. 8/24 approx 5:30pm; mid-tide (ebbing);clear; calm waters.
While scanning ocean-side waters for the continuing male Black Scoter, I was surprised to see a male White-winged Scoter (WWSC) approx 200 yds offshore. As I scoped the WWSC a big brown duck drifted through the lens. Assuming it was a Common Eider (several present) or possibly a female traveling companion WWSC, I delayed checking it to document the WWSC. Then, when I scoped it, I was stunned to see that it was a King Eider - the bird documented in this gallery. The bird was gradually drifting eastward away from shore when I left about 5:50. Typically, transient birds pausing at Duxbury Beach don't hang around very long. That said, the Black Scoter has been here for awhile; I will post to MassBird if I see it again.

In these photos, field marks for King Eider can be seen. Particularly obvious is the dark upturned gape line giving it the characteristic "smile". Also visible are the dark bill and head shape that differ from the Common Eider (see Sibley). Its size was essentially the same as the White-winged Scoter whereas the nearby Common Eiders were definitely a bit larger.

To help determine whether this was a Juvenile or Female, I took a good number of photos; however, due to the distance, even at full zoom, the photos provide insufficient feather detail for me to figure out which it is. Madge & Burns' book, Waterfowl, says the juvenile "Differs from female in being darker and greyer especially on head and neck... [has] broader dark markings along flanks..." and "Bill blacker than that of female...". So, the darker, less tawny look in the pix and in the field, lead me to suspect it is a juvenile. Perhaps viewers of these photos who are more familiar with the species can make a more certain call!