- Lifespan
- 15–20 years in the wild
- Size & Weight
- 53–58 cm, wingspan 132–148 cm; 1,200–1,600 g
- Habitat
- Open ocean and coastal waters; breeds on remote northern moorlands and islands with minimal vegetation.
- UK Distribution
- Summer breeder in northern Scotland, primarily in the Shetland and Orkney Islands; migratory, wintering in southern Atlantic and African waters.
- Diet
- Primarily fish and squid caught by diving; also obtains food through kleptoparasitism (forcing other seabirds to drop their catch) and predation on smaller seabirds.
- Prey
- Fish (especially sand eels), squid, kittiwakes, auks, and other seabirds
- Predators
- Golden eagles (on chicks); adults largely apex predators with few natural predators
- Mating Season
- April to August
- Breeding
- Clutch of 1–2 eggs; incubation period 27–29 days; fledging at 40–46 days; typically one brood per season.
- Behaviour
- Highly aggressive and territorial during breeding season, performing dramatic aerial attacks on intruders. Practiced kleptoparasites, chasing and harassing other seabirds to steal food mid-flight. Solitary or in small groups outside breeding season.