Justification of Red List Category
This species has declined rapidly over the past three generations and the decline is likely to be continuing. For these reasons the species is evaluated as Vulnerable.
The global population is estimated to number c. 14,600,000-15,700,000 (Wetlands International 2016). The European population is estimated at 1,730,000-2,200,000 pairs, which equates to 3,460,000-4,410,000 mature individuals (BirdLife International 2015).
Data collated from across Europe for the European Red List of Birds (BirdLife International 2015) indicate that the species has declined significantly in recent years, and that this decline is ongoing. A combination of official data reported by 27 EU Member States to the European Commission under Article 12 of the EU Birds Directive and comparable data from other European countries, provided by BirdLife Partners and other leading national ornithologists, suggests that the European population has declined markedly since the 1980s, and is currently estimated and projected to be declining overall at a rate of >40% over three generations (39 years, based on a generation length estimated by BirdLife to be 13 years). This corresponds well with the significant long-term decline reported by Berglund & Hentati-Sundberg (2014). Based on the latest population estimates (Coulson 2011, Wetlands International 2012), Europe (including Greenland) holds >50% of the global population. The small Canadian Arctic population is increasing by 1% per year (Mallory et al. 2009, Gaston et al. 2012), but as in Europe, the species’s breeding productivity in Alaska has declined since the 1980s, and numbers have decreased sharply in some colonies, possibly as a result of a regime shift in the North Pacific (Hatch 2013). At the regional scale of North America, which includes the NW Atlantic breeding population (c. 5% of the global population) and the NE Pacific breeding population (c. 15% of the global population), the species has recently been assessed as either stable or having undergone only a small decline (<15%) (North American Bird Conservation Initiative 2016). A recent analysis appears to show that the population in the North Pacific declined rapidly in the 1990s but has since recovered (Descamps et al. 2017). Global trends presented in the paper, however, appear to show that since 1975 the population size has declined by c.40%, which would place the global decline in the range of 30-49% over 3 generations (38.7 years).
This species nests in the North Atlantic, from NC Canada and NE USA east through Greenland to W & N Europe, and on to the Taymyr Peninsula and Severnaya Zemlya, wintering south to the Sargasso Sea and W Africa; and in the North Pacific, from NE Siberia, Kamchatka, Sea of Okhotsk and Kuril Is through Bering Sea to Alaska, wintering south to East China Sea and NW Mexico (Burger et al. 2016).
Behaviour This species is migratory and disperses after breeding from coastal areas to the open ocean (del Hoyo et al. 1996). It returns to its breeding grounds from January where it breeds from mid-May to mid-June in huge single- or mixed-species colonies (del Hoyo et al. 1996) that often exceed 100,000 pairs (del Hoyo et al. 1996, Snow and Perrins 1998). Breeding may occur later after periods of cold weather and many individuals do not remain on the breeding grounds during such conditions (del Hoyo et al. 1996). The species begins to disperse from the breeding colonies between July and August, often moulting in large flocks of several thousand individuals on beaches between the breeding grounds and the open sea (Olsen and Larsson 2003). Non-breeders may also remain at sea during the breeding season (Snow and Perrins 1998). Outside of the breeding season the species often occurs singly or in pairs (Snow and Perrins 1998) but may also occur in small flocks or as dispersed aggregations (Flint et al. 1984, Snow and Perrins 1998). Habitat Breeding It nests on high, steep coastal cliffs with narrow ledges in areas with easy access to freshwater (del Hoyo et al. 1996). Non-breeding The species moults on sandy beaches (Olsen and Larsson 2003) and on passage it may concentrate at sea on continental shelves, areas of upwelling (del Hoyo et al. 1996) 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 (del Hoyo et al. 1996). Diet 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 (del Hoyo et al. 1996) (e.g. crayfish) (Flint et al. 1984), earthworms, small mammals and plant matter (e.g. aquatic plants, potato tubers and grain) (del Hoyo et al. 1996). At sea during the winter it will also take planktonic invertebrates and often exploits sewage outfalls and fishing vessels (del Hoyo et al. 1996). Breeding site The nest is a compacted mass of mud (Snow and Perrins 1998), grass and feathers (Flint et al. 1984) usually built on a narrow ledge on high, steep coastal cliffs (del Hoyo et al. 1996). Occasionally the species may also nest on glaciers or snow banks (where these have covered traditional cliff nesting sites), on buildings and piers, or on flat, rocky or sandy sites up to 20 km inland (del Hoyo et al. 1996). It breeds in very large colonies with neighbouring nests spaced evenly 30-60 cm apart (where site availability allows) (Snow and Perrins 1998), and generally feeds within 50 km of the breeding colony (del Hoyo et al. 1996).
The species is threatened by the depletion of food resources (e.g. through over-fishing) (Frederiksen et al. 2004, Nikolaeva et al. 2006), marine oil spills (del Hoyo et al. 1996, Nikolaeva et al. 2006) and chronic oil pollution (Nikolaeva et al. 2006). It is also susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006). The species is potentially threatened by climate change because it has a geographically bounded distribution: its global distribution is restricted to within c.10o latitude from the polar edge of continent and within which 20-50% of current vegetation type is projected to disappear under doubling of CO2 levels (BirdLife International, unpublished data). It is caught as bycatch in longline fisheries, with significant numbers estimated to be caught off the western coast of Ireland and the U.K.. The species is considered a high risk for collision with offshore wind farms (Bradbury et al. 2014). The species is hunted in the Faroe Islands and in Greenland (Labansen et al. 2010, Thorup et al. 2014, 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 European Red List (BirdLife International 2015), 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. Sustainably manage fisheries to prevent over-fishing.
Text account compilers
Calvert, R., Malpas, L., Ekstrom, J., Ashpole, J, Butchart, S., Wheatley, H.
BirdLife International (2018) Species factsheet: Rissa tridactyla. Downloaded from http://www.birdlife.org on 21/03/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/03/2018.