The Great Black-backed Gull (GBBG) is the largest gull worldwide and can be found with regularity in many parts of New England. While not as numerous inland as Ring-billed and Herring Gulls, they are the third most common gull who I encounter. Adult birds are quite distinctive, with black-backs, pinkish legs, and large yellow bills marked with a red spot. Lesser Black-backed Gulls (LBBG), while similar in many respects, are substantially smaller birds, with lighter-colored backs and yellow legs. In New England, LBBGs are much less common, turning up most frequently in coastal locations in winter.
GBBGs take roughly four years to obtain adult plumage and in the process take on many different looks. Regardless of plumage variation, GBBGs stand out in a mixed flock of gulls, due to their impressively large size. The above photo shows an adult Great Black-backed Gull along with Herring and Ring-billed Gulls.