This question concerns an extra-limital gull I found on a Long Island, NY CBC on December 27th. Any opinions on an ID of this gull will be appreciated. Some theories that have been floated thus far include Luecistic GBBG, Leucistic HEGU, and Nelson's Gull. In the field, the bird was noticeably smaller than nearby GBBG and seemed larger than nearby HEGU. The flying shots are lousy, but give an idea of markings if you blow them up.
The photos are posted at: