Field Guide
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Great Black-backed Gull
Larus marinus
Not yet photographed by the community
Largest UK gull; powerful bill, near-black back.
Species Profile
Green List (UK)
- Lifespan
- 25–30 years in the wild, occasionally longer
- Size & Weight
- 64–78 cm, wingspan 150–165 cm; 1.3–2.0 kg
- Habitat
- Coastal cliffs, rocky islands, and occasionally inland lakes; breeds on remote islands and headlands with minimal disturbance.
- UK Distribution
- Resident year-round around much of the UK coast, with populations concentrated in Scotland, northern England, Wales, and south-west England; numbers augmented in winter by continental immigrants.
- Diet
- Highly opportunistic omnivore and scavenger; feeds on fish, crustaceans, seabirds, eggs, small mammals, and discarded refuse at landfills and fisheries.
- Prey
- Fish (especially flatfish), auks, other gulls, rabbits, rats, bird eggs, and offal from fishing vessels
- Predators
- Eggs and chicks preyed upon by foxes, mink, and corvids; adults rarely predated due to large size, though occasionally taken by white-tailed eagles
- Mating Season
- March to August, with peak activity April to June
- Breeding
- Clutch of 2–3 eggs; incubation period 26–29 days; fledging at 7–8 weeks; single brood per year; forms loose colonies and defends territories aggressively
- Behaviour
- Highly intelligent, adaptable, and increasingly bold around human settlements. Dominant and aggressive in interactions with other gull species and at feeding sites. Forms stable pair bonds and exhibits strong site fidelity, returning to natal colonies year after year.
- •Britain's largest gull and one of the heaviest gulls in the world
- •Can live over 30 years, with oldest ringed individuals recorded at 34+ years old
- •Capable of catching and eating other seabirds including auks, terns, and even young rabbits; known to kill and eat smaller gull chicks
- •Populations have increased substantially since the mid-20th century due to increased food availability from fishing discards and landfills, though recent declines have occurred due to fishing regulation changes
- •Pairs often nest in the same location for life and may defend territories for several decades
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