This gull was photographed on December 28, 2006 in the Coastal Plain near Houston and Galveston, Texas - note that was the size of a small-medium Herring gull:
The bill shape is thickish but probably not out of range for a male LBBG; the head shape has the "flattened dome" effect that I do not associate with LBBG; the wings look a bit short, and broad in the arm for LBBG; the innermost greater secondary coverts have a great deal of white (more white than black on the innermost three - a.k.a. humerals) for LBBG; the legs have more dark in them - on the rear as well as the front - than I've seen on any independant-from-parents large gull in the Northern Hemisphere (some of the Kelps I've seen in Chile have a similar leg color). This could be a big, dark, LBBG with some unusual features, but I wonder if this would stand out among first-cycle Kelp Gulls in one of the northernmost breeding areas in Brazil or Peru (where the nesting locations may be moving north, and nesting months may be closer to the range of dates known for Northern Hemisphere gulls)- ?:
