December 9th, 2004, Rochester WWTP, New Hampshire.
Kumlien’s Iceland or Thayer’s Gull Larus glaucoides kumlieni or Larus thayeri, juvenile/first-winter.
On December 13th, 2004, Martin Garner commented as follows;

"In brief your gull, as well as looking somehow anemic and uniform in plumage which is not right (especially the primaries) for Thayer's, also has new first-winter scapulars, typical of Kumlien's at this time of year and not right for many/most Thayer's at this time of year....a classic should be in full juvenile plumage. The primary projection also looks a little too short for Thayer's......again a feature noted on some dark first-winter Kumlien's.

My  assumption is that there is a whole range area where Thayer's is pure.....hence the consistency of west coast birds. Then there is a range where Thayers' and Iceland/ Kumlien's intergrade.....all of these birds from dark to nearly pale enough for glaucoides...should be called Kumlien's  and your bird fits a darker one of these."

NB. Martin Garner had authored numerous identification articles in Britain, including several papers concentrating specifically on the identification of Thayer’s Gull in Europe and its separation from Kumlien’s Iceland Gull. When I forwarded Martin’s comments to the ID-Frontiers listserve there were no serious challenges to his opinion concerning the identification of the Rochester bird.

One can find a number of Thayer’s Gull references on the internet which closely match the bird seen at Rochester on December 9th, 2004. Unfortunately, he bird was never seen again after these images were taken and the identification should probably be left undetermind. However, if this is a Kumlien's Iceland Gull it should serve as a very useful reference for darker individuals and problem birds.

From December 9th, 2004: Could this be a very dark kumlieni? Or possibly a Thayer’s Gull? Or possibly an intergrade between the two? This extremely interesting first-year gull was discovered amongst American Herring Gulls Larus (argentatus) smithsonianus and Great Black-backed Gulls Larus marinus at about 09:15hrs on the above date. About 12 Kumlien's Iceland Gulls Larus (glaucoides) kumlieni were also present at this site but none approached this bird in terms of the overall dark cast which wasn't too different from many of the juvenile/first-winter American Herring Gulls present.
 Images taken using a Nikon Coolpix 995 with Swarovski Habicht AT 80 HD telescope.
1) First noted resting amongst smithsonianus, the short legged appearance was immediately apparent.

 
2)  Rather small and delicate compared to surrounding smithsonianus.

3) Strong glare on the upperparts, but clearly on the dark side for a Kumlien's Iceland Gull.

 4) Primaries and centers of tertial much darker than rest of upperparts.
  5) A nice comparison with two smithsonianus.
kum:thayer21
6) A few gray (first-winter) scapulars are just beginning to emerge amongst the juvenile scapulars.
Page 1 of  3. The second page of images show some cropped details of this bird's plumage including a (poor quality) image of the raised wings showing the tail and uppertail coverts. Go to page 2. Go to page 3 with five new images.






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