Great Black-backed Gull

The Great Black-backed Gull is the largest gull species in the world, a powerful, imposing bird of North Atlantic coastlines with a commanding presence at any gathering of seabirds.

Adults have a very dark, blackish-slate mantle and upperwings — the darkest of the common black-backed gulls — contrasting sharply with a clean white head and body. The bill is massive and yellow with a red spot, and the legs are pink. Immature birds take about four years to acquire this striking adult plumage, passing through mottled brown stages similar to other large gulls.

Key field marks

• Very large size — the largest gull in the world
• Blackish-slate mantle and upperwings, darker than Herring or Lesser Black-backed Gull
• Massive, heavy yellow bill with a red spot
• Pink legs
• Powerful, bulky build with a large head

Similar species

• Lesser Black-backed Gull: smaller, with yellow (not pink) legs and a somewhat paler mantle in most populations.
• Herring Gull: notably smaller with a pale gray (not dark) mantle.
• Overall size and bulk, combined with the darkest mantle color among common large gulls, make adult Great Black-backed Gulls fairly straightforward to identify.

Habitat

Great Black-backed Gulls inhabit rocky and sandy coastlines, offshore islands, harbors, and adjacent open water, generally staying closer to the coast than venturing far inland.

Range and migration

They breed along the coasts of the North Atlantic, including eastern North America from the Canadian Maritimes and New England south along the coast, as well as coastal Europe. Many populations are resident or make only short-distance movements, though some individuals move farther south along the coast in winter.

Behavior

Great Black-backed Gulls are dominant and aggressive at feeding sites, often displacing smaller gulls, and are notable among gulls for actively hunting and killing other birds, including smaller seabirds, ducklings, and even adult birds up to the size of small waterfowl.

Voice

Calls include a deep, gruff "laughing" call, lower-pitched than that of the Herring Gull, reflecting the species' larger size.

Feeding

Their diet is broad and often predatory, including fish, other birds and their eggs and chicks, carrion, and refuse; they are capable of killing prey as large as other adult gulls and are frequent scavengers at fishing boats and landfills.

Nesting and breeding

They nest in loose colonies or as isolated pairs on coastal cliffs, offshore islands, and dunes; both parents share incubation of the typically three-egg clutch and defend the nest aggressively against intruders, including other gulls.