This 2nd cycle bird is a candidate for Kumlien's Iceland Gull, or is it something else (e.g. "Nelson's" Gull, i.e. Herring X Glaucous hybrid)? It was at Boyd Lake, Loveland, Colorado (USA) on 3 March 2008, seen by myself and Andrew Spencer.

Another observer reports seeing this bird at the same location on 2 March 2008, and considered it to be a Glaucous Gull.