Great Black-backed Gull (Larus marinus)
Overview: The Great Black-backed Gull is the largest gull in the world, with a hefty, stout body and broad wings. Blackish back and wings, white head and underparts. Head remains white and unstreaked in winter. White spots on wingtips, and, in flight, large white spot at tip of primaries. Legs and feet pale pinkish. Thick, heavy, yellow bill with a red spot on lower mandible. Pale eye with red eye ring.
A four-year gull. Juvenile is a large, bulky bird with a frosty tone. Back and wings checkered in tans, grays, and white; diffuse streaking on the neck and breast. Dark bill, dark eyes, pink legs. In flight shows almost white rump, checkered tail band. As it ages, the checkered plumage gradually transforms into the slaty gray of an adult, and the streaking fades, becoming clean white. Bill becomes bicolored then turns yellow. Third-year gulls look much like adult, but streakier and more unkempt.
Field Marks: Great Black-backed Gulls will be the largest gulls around—look for the huge size, big head and bill, and very broad wings. Black upperparts and pristine white underparts and head. Pinkish legs.
Size: 28 – 31 in.
Sounds: Harsh deep seal-like kyow or owk (listen to this bird here).
Behavior: The king of the Atlantic waterfront, the Great Black-backed Gull is the largest gull in the world, with a powerful build and a domineering attitude. They harry other birds to steal their food and even hunt adult birds such as grebes and puffins. The male establishes a small breeding territory, 10 to 20 feet in diameter, and the pair defends it against other gulls. Great Black-backed Gulls are monogamous and return to the same territory year after year. After chicks hatch the parents become especially aggressive. When terrestrial predators approach, the gulls dive and strike with their feet or wings, or rarely with their bills.
Habitat: Mainly coastal waters, estuaries, dumps; a few well inland on large lakes and rivers. Great Black-backed Gulls forage widely over the ocean, along shorelines, and at landfills and fishing docks. They rest or “loaf” in open areas such as parking lots, fields, runways, and piers. They breed in isolated places safe from terrestrial predators, such as small islands, rocky islets, saltmarshes, and barrier beaches.
Diet: Fish, mussels, crabs, sea urchins, other marine invertebrates, and birds; carrion, eggs and young of other birds; scavenges and steals food from other animals (including diving ducks, terns, puffins, murres, shorebirds, eagles, and sharks).
Fun Facts
The Great Black-backed Gull is the largest gull in the world. Its broad wings and powerful appearance give it a regal look that have impressed naturalists for years. In the words of one early observer: “It surely seemed to be a king among the gulls, a merciless tyrant over its fellows, the largest and strongest of its tribe. No weaker gull dared to intrude upon its feudal domain.”
During winter, large numbers of young Great Black-backed Gulls eat fish driven to the surface by humpback whales.
The Great Black-backed Gull is one of many bird species whose feathers were used for fashionable clothing in the 1800s. After the demise of the feather trade in the early 1900s, Great Black-backed Gull populations increased and spread farther south. Garbage dumps and other sources of human refuse have contributed to their range expansion.
Facts provided by the Cornell Lab of Ornithology.
Information compiled from multiple sources.