This is a different bird than the one photographed at Horseshoe Lake on 3 Dec 2014, see photos at www.pbase.com/quetzal/mysterygullaj. Features don't show well in this digiscoped image, but in the field we noted darker gray mantle compared to nearby Ring-billed and American Herring Gull, darker pink legs than nearby Herring, and darker eye than Herring. In this photo, the Vega is surrounded by Ring-billed Gulls (note paler mantle of Ring-billed). The gull in the foreground is California Gull. Note similar mantle shade with Vega.