Lake Merritt Gull on Jan. 8, 2012: This first-cycle gull was in the bird paddock with Western, Glaucous-winged, Ring-billed, and a few Thayer's Gulls at Lake Merritt on Sunday. It appears to be a Thayer's-type gull (meaning that it's either Thayer's or Kumlien's Iceland Gull; Icelandic Iceland Gulls do not occur in western North America). Glaucous-winged can probably be ruled out by its very small bill. Compared to the other Thayer's Gulls that were nearby, this bird seemed much, much paler, although the size and structure was similar to the other Thayer's. Notice especially the very extensive white in the checkered pattern on the back and the pale tertials. It is easily pale enough to be Kumlien's Iceland, but is it also dark enough to be a Thayer's?
On the other hand, there are a few features that seem wrong for anything in the Thayer's Gull complex. First off, the head is tall and poofy, but it seems to be sloped and rear-peaked, rather than rounded as on a Thayer's or Kumlien's. Also, the legs are a dull pale pink, unlike the "bubblegum legs" typical of Thayer's-group gulls. Might these features suggest that it's actually a Glaucous-winged Gull, albeit a very small-billed individual?