Very common on n. Atlantic coast, less numerous s.; often seen lounging on beaches. Scarcer inland. Survives frozen n. with help of huge bill. Scavenges but also kills live prey, including birds such as AMCO. ID: 4-yr gull. A real bruiser. Our largest gull, and bulky with a killer-like thick bill. Darkest-backed common gull with short wings. Dark colors add to mean appearance but overall impression is clean and bold. Younger birds contrasting plumage is neat and fairly distinctive. If in doubt, look at that bill. Ad br: dark gray-and-white. Bright yellow bill with red spot. Pink legs. Ad nonbr: a few dusky marks on head but still essentially white-headed. Some have black bill spot next to red. 3rd-yr: variable number of imm feathers in wing, variable black on bill and, generally, some black in tail. Juv to 2nd-s: superficially similar with boldly checkered upperparts and well-defined markings on underparts. Pale-headed. Strongly patterned tail. Juv: mantle and scapulars show fairly uniform dark centers and broad pale fringes. New feathers, molted through first winter, have more complicated internal markings. Bill typically mostly dark until 2nd-s when start to get dark adult-like mantle.