- Lifespan
- 20–30 years in the wild, with some individuals recorded living over 34 years
- Size & Weight
- 32–35 cm long, wingspan 75–85 cm; 85–105 g
- Habitat
- Coastal and inland breeding sites including islands, shingle beaches, moorland, and Arctic tundra; open ocean during migration and winter.
- UK Distribution
- Summer breeder (May–August) across northern and western Scotland, northern England, Wales, and Ireland. Rare vagrant to southern England during migration periods. Absent in winter.
- Diet
- Primarily small fish caught by aerial diving, including sand eels, sprats, and small herrings; occasionally takes small crustaceans.
- Prey
- Sand eels, sprats, small herrings, capelin, and occasionally small crustaceans
- Predators
- Great Black-backed Gulls, Herring Gulls, corvids (crows and ravens), and occasionally Merlins; eggs and chicks also predated by foxes and rats
- Mating Season
- May to August
- Breeding
- Typically 1–2 eggs per clutch; incubation period 21–24 days; single brood per year; chicks fledge at 28–35 days old
- Behaviour
- Highly migratory, undertaking the longest migration of any bird species, traveling roughly 70,000 km annually between Arctic and Antarctic regions. Highly vocal and territorial during breeding season; pairs perform synchronized courtship displays. Colonial breeder, often nesting in loose groups.