A sub-adult Great Black-backed Gull was spotted at Rist Benson Lake in Loveland (Larimer County, Colorado, USA) on January 14, 2006, by Roger Sleeper. I photographed it on Jan 16 and 17. It is apparently a fourth-cycle bird in basic ("winter") plumage. This species is rare enough to be on the Colorado Bird Record Committee Review List. We probably see about one per year in Larimer County, in winter.