Below, Christopher reveals some more shots of the bird and discusses this bird's identity. Our first impression may be of Franklin's Gull given the bird's small size compared to the Ring-billed Gull and the dark cap that is more like an adult basic Franklin's Gull. Still, several features do not fit a typical Franklin's Gull. The very long-winged look is more like that of a Laughing Gull, as are the long legs and slender build. Further, the primary tips are less prominent than on an adult Franklin's Gull at this time of year.
Gulls always become easier when the wings are open.
These photos reveal extensive dark outer primaries on both the upperwing and underwing. This bird, however, is outside the range of a Franklin's Gull since the entire outer half of the primaries are dark from below. Further, the primary coverts are those of an adult and the tail is white tail. This bird has uniform coverts and tail, typical of an adult bird. This bird has started molting head feathers, which accounts for the more extensive hood than is present on most adult basic Laughing Gulls.