Archived 2015 topics: Common Eider (Somateria mollissima) – uplist from Least Concern to Near Threatened or Vulnerable?

Common Eider Somateria mollissima is distributed over the northern coasts of Europe, North America, eastern Siberia and southern Greenland. It breeds in the Arctic and northern temperate regions, but its range expands during winter to as far south as New Jersey, southern Alaska, the western Mediterranean and Kamchatka (Carboneras 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 (>3 million km2) and in winter (>5 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 (3.3–4.0 million individuals; 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 end of the last century, and is currently declining overall at a rate of >40% over three generations (27 years, based on a generation length estimated by BirdLife to be 9 years). This corresponds well with the decline evident since the late 1990s in the largest flyway population of S. m. mollissima in the Baltic and Wadden Seas, based both on breeding data (Ekroos et al. 2012) and on midwinter counts conducted as part of the International Waterbird Census (Nagy et al. 2014). Consequently, the species is now classified as Vulnerable at European level (BirdLife International 2015).

Based on the latest population estimates (Wetlands International 2012), Europe (including Greenland) holds >60% of the global population, so the declines in Europe are globally significant. A variety of factors may be driving the decline (Waltho & Coulson 2015), which would have been even steeper if the long-term decline in Greenland not been reversed by a change in harvest regulations in 2001, which allowed the population in part of W Greenland to recover and quintuple in just 11 years (Burnham et al. 2012).

Most of the rest of the global population occurs in North America, for which Bowman et al. (2015) summarise the situation as follows: “Limited available data on the Pacific population S. m. v-nigra [c. 4% of global] suggest that it declined in northern parts of its range between the 1980s and early 2000s; more recently, it has declined in central arctic Canada and NW Alaska, but is stable or increasing elsewhere in Alaska. The data on the American population S. m. dresseri [c. 9% of global] show variable trends, with increases in the north and declines in the south. The trends of the other two populations, Hudson Bay S. m. sedentaria [c. 6% of global] and Northern S. m. borealis [c. 16% of global], are uncertain.”

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 to qualify for uplisting to at least globally Near Threatened and possibly Vulnerable under criterion A.

Comments on this proposal are welcome, along with any data regarding recent trends in other regions, and any additional information about the threats currently affecting this species across its range.

References

BirdLife International (2015) European Red List of Birds. Luxembourg: Office for Official Publications of the European Communities. http://www.birdlife.org/datazone/info/euroredlist

Bowman, T. D., Silverman, E. D., Gilliland, S. G., & Leirness, J. B. (2015). Status and trends of North American sea ducks: reinforcing the need for better monitoring. Pp. 1-28 in Savard et al., eds. Ecology and Conservation of North American Sea Ducks. Studies in Avian Biology 46.

Burnham, K. K., Johnson, J. A., Konkel, B., & Burnham, J. L. (2012). Nesting common eider (Somateria mollissima) population quintuples in Northwest Greenland. Arctic, 456-464.

Carboneras, C., Christie, D.A. & Kirwan, G.M. (2014). Common Eider (Somateria mollissima). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. www.hbw.com

Ekroos, J. et al. (2012) Declines amongst breeding Eider Somateria mollissima numbers in the Baltic/Wadden Sea flyway. Ornis Fennica 89: 81-90.

Nagy, S., Flink, S., Langendoen, T. (2014) Waterbird trends 1988-2012: Results of trend analyses of data from the International Waterbird Census in the African-Eurasian Flyway. Wetlands International, Ede. http://www.wetlands.org/Portals/0/TRIM%20Report%202014_10_05.pdf

Waltho, C., & Coulson, J. (2015). The Common Eider. Bloomsbury Publishing.

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

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8 Responses to Archived 2015 topics: Common Eider (Somateria mollissima) – uplist from Least Concern to Near Threatened or Vulnerable?

  1. Ian Burfield (BirdLife) says:

    The following information about this species in Iceland was kindly provided by Gudmundur A. Gudmundsson during the compilation of the European Red List:

    The estimate of 850,000 Eiders in Iceland in winter is based on aerial surveys of coastal waters in 2008 (Gardarsson 2009). Trends based on mid-winter counts 1952-2014 show stability until late 1960 and steady increase (+100%) till 2000 (2,2% per year), but steady decline after 2000 to present (-33% or 2.9% per year). Overall long term trend 1960-2014 is still positive (IINH, unpublished) and 1980-2014 is in level („stable“).

    A combined population index was calculated by summing annual nest counts in 17 colonies with data for 1977-2000 but calculating with 40 colonies for 2001-2007. Number of eider nests generally increased 1980-1990, except for Southwest Iceland where numbers remained stable. There were three types of trends 1990-2007: 1) nest numbers declined in North Iceland, Westfjords and in Breiðafjörður except for the West islands; 2) nest numbers remained stable in the West islands of Breiðafjörður; and nest numbers increased 1995-2000 in Southwest Iceland but were stable 2001-2007 (J.E. Jónsson et al., in prep).

    Gardarsson, A. 2009. Number of Common Eider, Long-tailed Duck, Red-breasted Merganser and Mallard, wintering on the coast of Iceland. Bliki 30: 49-54. (In Icelandic with an English summary).
    Jónsson, J.E, et al., in prep. Trends in Nest Numbers of Common Eider in Iceland.

  2. Ib Krag Petersen says:

    Given the c.6.3 % per annum decline in the Baltic-Wadden Sea Common Eider Somateria mollissima population since the early 1990s and the reduction in the male/female ratio among shot birds from 3:2 to about 3:1 over the same period, we support the change in status of the species, especially with regard to the declines in this element of the global population.

    In response to the specific concerns raised in Denmark regarding the conservation status and sustainability of contemporary levels of exploitation there, the hunting season on the species was shortened by 44 and 46 days for females and 13 and 15 days for males from the hunting seasons 2004/2005 and 2011/2012 onwards, respectively (Christensen & Hounisen 2014). The aims of these changes were to reduce the kill overall and specifically to relax the hunting of females in relation to males which were contributing an increasing proportion of the population as a whole as overall numbers declined. These measures reduced the kill of adult females by 82 %, adult males by 31 %, juvenile females by 58 % and juvenile males by 55 %. The observed reduction in the kill of adult females following both changes in 2004/2005 and 2011/2012 matched the expected changes based on the seasonal distribution of sexes in the bag prior to the change (Christensen & Hounisen 2014). Post 2004/2005 hunters killed more adult males, but also shot markedly fewer juvenile birds than expected. Demographic modelling of the female population showed that the effects of the reduced hunting would correspond to an increase in the annual population growth rate from the previous −6.3 to −3.6 % (post 2004) and −1.6 % (post 2011). The model also predicted that a full ban on hunting female eiders (adults and juveniles) would lead to a positive population growth rate of 0.7 % (Christensen & Hounisen 2014). The results of monitoring of this population suggests some stabilization in the Danish wintering population following the implementation of these changes in hunting, with a country total of 155,615 counted in January 2013 (Pihl et al 2015) compared to 138,834 in the previous full countrywide survey in 2008 using the same methods (Pihl et al 2013).

    However, we urgently need to look at patterns of change in distribution and abundance at the flyway level before we can draw any final conclusions about the effects of changes in hunting at the population level. Taking into account the conservative model estimates and natural variations in annual breeding success, the implemented changes in sex-specific regulation of hunting may potentially be an effective management tool to halt the decline of the Baltic-Wadden Sea eider population, potentially rendering such levels of hunting sustainable under prevailing conditions. We continue to urge for better methods and international coordination of this and other Common Eider populations around the globe, as well as other sea duck populations in the Baltic/North Seas and elsewhere to better understand their distribution, abundance and trends in annual population change to better manage these species.

    Christensen, T.K. & Hounisen, J.P. 2014. Managing hunted populations through sex-specific season lengths: a case of the Common Eider in the Baltic-Wadden Sea Flyway Population.European Journal of Wildlife Research 60: 717-726.

    Pihl, S., Clausen, P., Petersen, I.K., Nielsen, R.D., Laursen, K., Bregnballe, T., Holm, T.E. & Søgaard, B. (2013): Fugle 2004-2011. NOVANA. Research report from Danish Centre for Environment and Energy, Aarhus University No. 49. 188 pp. (in Danish) http://dce2.au.dk/pub/SR49.pdf

    Pihl, S., Holm, T.E., Clausen, P., Petersen, I.K., Nielsen, R.D., Laursen, K., Bregnballe, T. & Søgaard, B. 2015. Fugle 2012-2013: NOVANA. Research report from Danish Centre for Environment and Energy, Aarhus University No. 125. 170 pp. (in Danish) accessible at http://dce2.au.dk/pub/SR125.pdf

  3. Breeding Common Eider has declined at Forvie National Nature Reserve, North-East Scotland since intensive records began in 1991. The Spring peak population has declined from 5048 birds in 1991 to 1639 birds in May 2015. The causes of decline are undetermined given review of intensive predator control, management of recreation and investigation into local food supply. Data held by Scottish Natural Heritage is available on request to assist wider study into overwintering and breeding populations on east coast UK.

  4. Chris Waltho says:

    The eiders in south west Scotland (Firth of Clyde) are geographically isolated from those the in Baltic-Waddensea or anywhere else in Europe. In 2000, this population accounted for >20% of British Isles eiders. The population trend has declined by 65% since 1997, at 7% per annum. However, this decline followed an extended period of colonisation and population growth over previous 90 years (at 9.3% per annum), the result of southward range expansion that has been underway since approximately 1850. The causes of this decline are currently unknown, but are likely the combination of several different factors.

    Waltho, C., & Coulson, J. (2015). The Common Eider. Bloomsbury Publishing.

    Statement in paper
    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 to qualify for uplisting to at least globally Near Threatened and possibly Vulnerable under criterion A.

    Comment
    The European Red List assessment accounts for around 2/3 of the global eiders, and includes any numerical buffering effects from the large populations in Iceland and Norway/NW Russia. As there is no obvious and widespread growth evident in North American and NE Russian populations to warrant adopting Near Threatened status, the precautionary principle suggests that Vulnerable should be applied globally at this time.

  5. Andy Symes (BirdLife) says:

    Hans Meltofte, chairman of the conservation committee of DOF/BirdLife Denmark, has provided the following comment:

    The evaluation of some other species is critical as well. For Common Eider, Eurasian Oystercatcher and Herring Gull decreases may primarily or at least partly be due to reductions in the eutrophication from agriculture that a number of successful water quality improvement efforts have resulted in – together with reduced offal from fishing vessels and open rubbish dumps for the Herring Gull. In other words, marked increases in these species during the 20th century were more or less artificial, and we risk to make ourselves completely ridiculous by claiming that declines in these species are a problem, if populations are just returning to sizes reflecting the carrying capacity of the natural (non-eutrophicated) environment.

  6. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2015 Red List would be to treat:

    Common Eider as Near Threatened under criterion A4.

    However, further information, especially from populations in North America, would be very helpful.

    There is now a period for further comments until the final deadline of 31 August, after which the recommended categorisation 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.

  7. Kjell Larsson says:

    On the island of Gotland in the central Baltic Sea surveys of nesting eider females at 26 breeding sites have shown a dramatic decline in numbers from approx. 7140 nesting females in year 2007 to approx. 2560 in 2011 and further down to approx. 1310 in 2015. On the island of Öland where breeding eiders previously have been common, nesting eiders were almost totally absent in 2015. These continuing rapid declines even in the most recent years cannot be explained by reversed eutrophication effects. Concentrations of N and P in water in the central and northern Baltic Proper has not declined very much in recent years. Inflow from land has declined but not the concentrations in sea water. One should also note that breeding success has not been synchronous among regions within the Baltic Sea during the past nine years. Reductions of concentrations of P and N in water in southern and southwestern Baltic, i.e. at the common wintering ground can hardly explain the recent decline of breeding eiders in central and northern Baltic Proper.

  8. 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.

Comments are closed.