The Lesser Black-backed Gull (Bird Code: LBBG) is primarily a species of Europe, but in recent decades has been turning up in North America in larger numbers.* LBBGs average smaller than Herring Gulls (HERG), but larger than Ring-billed Gulls (RBGU). Adult birds have gray mantles that are darker than those of HERGs or RBGUs, but not as dark at those of Great Black-backed Gulls (GBBGs). The following photo shows an adult LBBG with an adult GBBG. In addition to the size and color differences, notice the yellow legs of the LBBG, versus the pink legs of the GBBG.
The first Lesser Black-backed Gull I ever saw was with a mixed flock of gulls (that included at least one Iceland Gull) at a mostly ice-covered reservoir in Rhode Island. Can you pick out the LBBG in the following crowded scene? (See full-size).
*In 2007, a LBBG nested with a HERG on Appledore Island in Maine. This was the first US east coast breeding record.