Great Black-backed Gull

Fascinating facts about the Great Black-backed Gull

• At up to 2.5 kg (5½ lb), the great black-backed gull can outweigh most seaside birds, making it the heaviest gull that regularly breeds in the North Atlantic and giving it the brute force to wrestle prey as big as a 750 g (26 oz) duck right out of the air. This size lets it hunt like a raptor, reshaping how we view gulls as mere scavengers.
• It has a wingspan of 1.5–1.7 m and a bill length of 5.4–7.25 cm.
• In a 2009 North Atlantic sample, males averaged 1,830 g while females averaged 1,488 g, and gulls with access to North Sea fisheries averaged about 1.96 kg (4 lb 5 oz).
• Only 19 % of the time do these gulls actually eat at Massachusetts dump sites; the rest they spend roosting or loafing. Even though they dominate the landfill scene, they consume far less garbage than other gull species, highlighting a selective opportunism rather than pure waste dependence.
• Juveniles take at least four years to reach maturity, and by the third year they still look “dirtier” than adults.

At a glance

About the Great Black-backed Gull

The great black-backed gull (Larus marinus) dominates the North Atlantic sky as the world’s largest gull, a bulky bird measuring 64–79 cm in length with a 1.5–1.7 m wingspan and weighing up to 2.5 kg where fisheries are abundant. Its stark white head, neck and underparts contrast sharply with blackish-grey wings and back, while pink legs and a yellow bill tipped with a red spot give it a regal appearance. Juveniles start out with scaly, checkered brown plumage that slowly fades over four years, eventually revealing the adult’s imposing silhouette and deep, laughing "kaa-ga-ga" call that echoes over cliffs and estuaries. These gulls breed on rugged coasts from northern Norway and northwest Russia to the United Kingdom, Ireland and the Atlantic shores of Canada and the United States, nesting on predator-free islands, dunes, rooftops and even the dredge spoils of New Jersey. In winter they roam far out to sea or follow ice edges in the Baltic, occasionally venturing inland to large lakes, ponds and refuse dumps where they scavenge more than half of their diet. Their opportunistic feeding ranges from swallowing whole fish, capelin, cod, herring and mackerel, to pirating prey from other birds, hunting seabird eggs, and even tackling small mammals. A surprising trait is their raptor-like aggression: they will chase and jab at flying birds, sometimes killing adults up to 750 g, a behavior more akin to a hawk than a typical gull.

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