VU
Black-legged Kittiwake Rissa tridactyla



Justification

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 it is evaluated as Vulnerable.

Population justification
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).

Trend justification
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). This corresponds well with the significant long-term decline reported by Berglund and 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 populations breeding in the Northwestern Atlantic (c. 5% of the global population) and in the Northeastern Pacific (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 three generations (39 years).

Distribution and population

This species breeds in the North Atlantic, from northern central Canada and northeastern U.S.A. east through Greenland to western and northern Europe, and on to the Taymyr Peninsula and Severnaya Zemlya (Russia), wintering south to the Sargasso Sea and West Africa; and in the North Pacific, from northeastern Siberia, Kamchatka, Sea of Okhotsk and Kuril Islands through the Bering Sea to Alaska, wintering south to the East China Sea and northwestern Mexico (Burger et al. 2016).

Ecology

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 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, 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 (del Hoyo et al. 1996). On passage, it may concentrate at sea on continental shelves, areas of upwelling and at rich fish banks (del Hoyo et al. 1996, 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 (e.g. crayfish), earthworms, small mammals and plant matter (e.g. aquatic plants, potato tubers and grain) (Flint et al. 1984, 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, grass and feathers, usually built on a narrow ledge on high, steep coastal cliffs (Flint et al. 1984, del Hoyo et al. 1996, Snow and Perrins 1998). 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).

Threats

Trophic shifts in the Atlantic appear to have removed the prey base for a large proportion of the population over a relatively short timeframe, and these appear largely to be due to climate change. Both large spills and ongoing chronic oil pollution are impacting populations of this species (Nikolaeva et al. 2006), and may be contributing to reduced prey abundance and poor adult condition resulting in lowered reproductive output. Certain fisheries may also have contributed to depleted food resources for the species (Frederiksen et al. 2004, Nikolaeva et al. 2006), exacerbating population declines due to increased foraging effort and nutritional stress leading to greater adult mortality or breeding desertion (Paredes et al. 2014). Black-legged Kittiwakes also suffer a level of bycatch in longline fisheries, especially the Spanish Gran Sol longline fishery (BirdLife International 2015), for which there is virtually no monitoring of bycatch and none of the vessels operating in the fishery are currently MSC-certified (E. Dunn in litt. 2018). However, there is virtually no bycatch of kittiwakes in the northern Atlantic, with the species noted to be adept at removing prey without capture at least where the hooks are large (Løkkeborg 1990, Dunn and Steel 2001, E. Dunn in litt. 2018). Avian flu has been recorded in the species, but to date only in very few individuals and without any indication of impacts at the population level (Melville and Shortridge 2006). There is a possibility that a future outbreak could lead to significant mortality within a breeding colony.

Conservation actions

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, Portugal and Spain.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 the creation of 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.

Acknowledgements

Text account compilers
Ekstrom, J., Ashpole, J, Malpas, L., Calvert, R., Martin, R., Butchart, S., Pearmain, L., Wheatley, H.

Contributors
Dunn, E., O'Connell, P.


Recommended citation
BirdLife International (2019) Species factsheet: Rissa tridactyla. Downloaded from http://www.birdlife.org on 22/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/11/2019.