Black-legged Kittiwake (Rissa tridactyla) – request for information from North Pacific

This discussion was first published as part of the 2015 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2017 Red List update this post remains open and the date of posting has been updated.

Black-legged Kittiwake (Rissa tridactyla) breeds 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. 2014). It is currently listed as Least Concern, because when last assessed it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.

Globally, it has an extremely large range in both the breeding season (>1.6 million km2) and in winter (>50 million km2), and hence does not approach the thresholds for Vulnerable under the range size criteria (B and D2). Its population size is also extremely large (14–16 million individuals; Coulson 2011, Wetlands International 2012), and hence does not approach the thresholds for Vulnerable under the population size criteria (C and D1). Therefore, the only potentially relevant criterion is A, which relates to reductions in population size. Until recently, the population was thought to be declining slowly, but not sufficiently rapidly to approach the threshold for listing as Vulnerable under criterion A (at least a 30% decline over ten years or three generations, whichever is longer).

New 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). Consequently, the species is now classified as Vulnerable at European level (BirdLife International 2015).

Based on the latest population estimates (Coulson 2011, Wetlands International 2012), Europe (including Greenland) holds >50% of the global population, so the declines in Europe are globally significant. 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’ 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). However, no recent information is available about the overall trend of the North Pacific population.

Given the size of the European population, the magnitude and scale of recent ongoing declines in Europe, and the absence of any evidence of compensatory increases elsewhere in its range, this species appears likely to qualify for uplisting from Least Concern under criterion A. To complete the global picture and inform which category is most appropriate, data are sought on recent overall trends in the North Pacific, along with any additional information about the threats currently affecting this species across its range.


Berglund, P. A. & Hentati-Sundberg, J. (2014). Arctic Seabirds Breeding in the African-Eurasian Waterbird Agreement (AEWA) Area: Status and Trends 2014. AEWA Conservation Status Report (CSR6) background report.

BirdLife International (2015) European Red List of Birds. Luxembourg: Office for Official Publications of the European Communities.

Burger, J., Gochfeld, M., Kirwan, G.M. & Christie, D.A. (2013). Black-legged Kittiwake (Rissa tridactyla). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2013). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.

Coulson, J. (2011). The Kittiwake. Bloomsbury Publishing.

Gaston, A. J., Mallory, M. L., & Gilchrist, H. G. (2012). Populations and trends of Canadian Arctic seabirds. Polar biology, 35(8), 1221-1232.

Hatch, S. A. (2013). Kittiwake diets and chick production signal a 2008 regime shift in the Northeast Pacific. Mar Ecol Prog Ser, 477, 271-284.

Mallory, M. L., Akearok, J. A., Gaston, A. J. (2009) Status of High Arctic Black-Legged Kittiwake (Rissa tridactyla) Colonies in Barrow Strait, Nunavut, Canada. Arctic 62: 96-101.

Wetlands International (2012) Waterbird Population Estimates: 5th edition.

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6 Responses to Black-legged Kittiwake (Rissa tridactyla) – request for information from North Pacific

  1. W.R.P. Bourne says:

    The Atlantic Black-legged Kittiwakes underwent an increase in the recent past which could be attributed to over-exploitation of the large fish which compete with it for food. If this is now increasing again it will explain a decline. The same could apply in the Pacific but we have less information there.

  2. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2015 Red List would be to pend the decision on Black-legged Kittiwake and keep this discussion open until 2016, while leaving the current Red List category unchanged in the 2015 update.

    Information from the north Pacific is needed before the global status can be resolved.

    There is now a period for further comments until the final deadline of 31 August, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes (BirdLife) says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposal for the 2015 Red List status of this species.

    The final categorisation will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessment by BirdLife and IUCN.

  4. Ian Burfield (BirdLife) says:

    The State of North America’s Birds 2016 ( presents the results of a regional conservation vulnerability assessment for all 1,154 native bird species that occur in Canada, the continental United States and Mexico. It was published too late for BirdLife to review and take fully into account for the 2016 update to the global IUCN Red List. However, it has been consulted for relevant information about the subset of species whose global status is currently under discussion on BirdLife’s Globally Threatened Bird Forum. If resources allow, its implications for other species will be considered in 2017.

    At the regional scale of North America, Black-legged Kittiwake is assessed as having an aggregate vulnerability score of 8, out of a maximum of 20 (for more details of the scoring method, see Panjabi et al. 2012). It is therefore not currently considered to be of high conservation concern in North America. One element of this aggregate score relates to the species’ population trend, with a score of 1 equating to a large increase and 5 to a large decline. Black-legged Kittiwake has a population trend score of 3, denoting that overall it is currently thought to be either stable or have undergone only a small decline (<15%).

    These North American figures combine data from the NW Atlantic breeding population of R. t. tridactyla (c. 5% of the global population) and the NE Pacific breeding population of R. t. pollicaris (c. 15% of the global population). Knowing that overall they are either stable or have declined a little is useful, but it still leaves a large gap in our knowledge about the population trend of the much larger population of R. t. pollicaris breeding in the NW Pacific. That population is thought to hold at least 30% of the global population (with 1.6 million pairs estimated in Kamchatka alone; Wetlands International 2012).

    To complete the picture and correctly assign the correct global Red List status to this species, it is therefore imperative to understand how it is faring in NE Russia. Relevant contributions would be warmly welcomed.

    Panjabi, A. O., P. J. Blancher, R. Dettmers, and K. V. Rosenberg (2012) Handbook on Species Assessment. Partners in Flight Technical Series No. 3. Rocky Mountain Bird Observatory website:

    Wetlands International (2012) Waterbird Population Estimates: 5th edition.

  5. James Westrip (BirdLife) says:

    Based on available information, our proposal for the 2016 Red List would be to pend the decision on this species and keep this discussion open until 2017, while leaving the current Red List category unchanged in the 2016 update.

    Final 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  6. James Westrip (BirdLife) says:

    Recently published work by Descamps et al. (2017) presents regional and global data on Black-legged Kittiwake. Regional analysis appears to show that the population size in the North Pacific declined rapidly in the 1990s but has since recovered. 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).

    Descamps, S.; Anker-Nilssen, T.; Barrett, R. T.; Irons, D. B.; Merkel, F.; Robertson, G. J.; Yoccoz, N. G.; Mallory, M. L.; Montevecchi, W. A.; Boertmann, D.; Artukhin, Y.; Christensen-Dalsgaard, S.; Erikstad, K.-E.; Gilchrist, H. G.; Labansen, A. L.; Lorentsen, S.-H.; Mosbech, A.; Olsen, B.; Petersen, A.; Rail, J.-F.; Renner, H. M.; Strøm, H.; Systad, G. H.; Wilhem, S. I.; Zelenskaya, L. 2017. Circumpolar dynamics of a marine top-predator track ocean warming rates. Global Change Biology DOI: 10.1111/gcb.13715

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