- Lifespan
- 15–20 years in the wild; some individuals recorded living over 30 years
- Size & Weight
- 37–39 cm; wingspan 70–82 cm; 380–500 g
- Habitat
- Coastal cliffs and rocky outcrops where they nest in colonies, spending winters at sea over deep Atlantic and North Sea waters.
- UK Distribution
- Breeds at scattered colonies around UK coasts, particularly in Scotland (St Kilda, Orkney, Shetland), northern England, and Wales; migratory, wintering in the Atlantic.
- Diet
- Small fish and crustaceans caught by plunge-diving and surface-feeding; primarily sand eels, sprats, and capelin.
- Prey
- Sand eels, sprats, capelin, small fish, and occasionally small crustaceans
- Predators
- Great skuas, lesser black-backed gulls, and occasionally peregrine falcons; eggs and chicks vulnerable to herring gulls and ravens
- Mating Season
- April to August
- Breeding
- Clutch of 1–3 eggs (usually 2); incubation period 25–32 days; fledglings leave nest at 32–39 days; typically one brood per year
- Behaviour
- Highly social, nesting in large, noisy colonies where pairs engage in ritualistic head-nodding and mutual preening. They are faithful to breeding sites and partners year after year. Known for their distinctive three-toed foot (hence tridactyla), lacking the hind toe of other gulls.