In Europe this species breeds on cliffs and coastlines in both Arctic and temperate regions. This species is migratory and disperses after breeding from coastal areas to the open ocean (Burger et al. 2016). It returns to its breeding grounds from January where it breeds from mid-May to mid-June in huge single- or mixed-species colonies (Burger et al. 2016) that often exceed 100,000 pairs (Snow and Perrins 1998, Burger et al. 2016). Non-breeders may also remain at sea during the breeding season (Snow and Perrins 1998). It nests on high, steep coastal cliffs with narrow ledges in areas with easy access to freshwater (Burger et al. 2016). The species moults on sandy beaches (Olsen and Larsson 2003) and on passage it may concentrate at sea on continental shelves, areas of upwelling (Burger et al. 2016) and at rich fish banks (Olsen and Larsson 2003). During the winter the species is highly pelagic, usually remaining on the wing out of sight of land (Burger et al. 2016). Its diet consists predominantly of marine invertebrates (e.g., squid and shrimps) and fish, although during the breeding season it may also take intertidal molluscs, crustaceans (Burger et al. 2016) (e.g., crayfish) (Flint et al. 1984), earthworms, small mammals and plant matter (e.g., aquatic plants, potato tubers and grain) (Burger et al. 2016). Many species of fish have been recorded in diet, but sandeels (Ammodytes), capelin (Mallotus villosus) and herring (Clupea harengus) are particularly important (Burger et al. 2016).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

The species nests along coastlines in much of the Atlantic ocean, notably in Iceland, Svalbard and Jan Mayen, Russia, the United Kingdom, the Faroe Islands, Greenland and Norway. It winters at sea, ranging across much of the north Atlantic (Burger et al. 2016).

Conservation Actions Underway
The species is listed under the African-Eurasian Waterbird Agreement, but is not listed on the Bern Convention, the Convention of Migratory Species or on the EU Birds Directive Annexes. It is protected in some European countries by national legislation, including: France ( ‘Liste des espèces d’oiseaux protégées en France en application de l’article L. 411-1 du code de l’environnement et de la directive 79/409 du 2 avril 1979 concernant la conservation des oiseaux sauvages’); Portugal (D.L. 140/99 de 24 de Abril rectificado pelo D.L. 49/2005 de 24 de Fevereiro; Spain (species listed on the State Catalogue of Threatened Species as a species of “Special Interest” – Royal Decree 439/1990 & under regional legislation and included on the Galician Catalogue of Threatened Species: “Vulnerable” Decree 82/2007 of 19th of April). The species is categorised as Vulnerable in the Norwegian Red List and the All-Ireland Vertebrate Red Data Book (OSPAR, 2010). Population monitoring occurs across much of its breeding range, including Greenland, Norway (Anker-Nilssen et al. 2007), Iceland (Garðarsson 2006) France and the U.K.. The species is considered within the Nordic Action Plan for Seabirds.

Conservation Actions Proposed
The species could benefit from regional level, international Species Action Plans, a regional monitoring strategy and further research on the effects on climate change and prey reductions. OSPAR recommends creating a network of hunting-free reserves in coastal areas. Monitoring of bycatch of this species through on board observer programmes is needed, and appropriate mitigation measures implemented where necessary. Sustainable manage fisheries to prevent over-fishing.