Archived 2011-2012 topics: Greater Scaup (Aythya marila): uplist to Near Threatened or Vulnerable?

Initial deadline for comments: 31 January 2012.

BirdLife species factsheet for Greater Scaup

Greater Scaup Aythya marila breeds in tundra and moorland in northernmost Europe, Asia and North America, and winters in shallow coastal waters and occasionally inland water bodies south of its breeding grounds. The species is currently listed as Least Concern on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria.

This species has an extremely large range (Extent of Occurrence [EOO] in the breeding season estimated at c.7.83 million km2, wintering EOO c.4.98 million km2) and hence does not approach the thresholds for Vulnerable under the range size criteria (B and D2: EOO of less than 20,000 km2, combined with a declining or fluctuating range size, habitat extent/quality or population size, and a small number of locations or severe fragmentation). The population size is also extremely large (c.1.2 million individuals; Wetlands International 2006), and hence does not approach the thresholds for Vulnerable under the population size criteria (C and D1: fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure). Therefore, the only 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).

An analysis of Christmas Bird Count data collected since the mid-1960s suggests that an annual population change of -3.4% has occurred across c.85% of the species’s range in North America, indicating a 75% decline between 1965-1966 and 2005-2006 (Butcher and Niven 2007), and suggesting a decline of c.57% over the last three generations, estimated by BirdLife to be c.25 years (based on a generation length of c.8.2 years), assuming an exponential trend. In addition to this rapid decline, survey results from the Baltic Sea suggest that the species has declined there as a wintering species, from an estimated 146,000 individuals in 1992-1993 to 127,000 individuals in 2007-2009, suggesting a decline of c.13% in c.16 years (Skov et al. 2011). This is equivalent to a decline of c.20% over the last three generations.

Together, the north-west European and North American populations comprise around two-thirds of this species’s global population (Wetlands International 2006), so these declines are of potentially global significance. The rates of decline recorded in North America (c.44% of the estimated global population) and the Baltic Sea (c.24% of the estimated global population) suggest that overall the species has declined by at least c.30% over three generations, assuming that the other populations (c.32% of the estimated global population) are stable. No trend information is available for these other two populations (western Siberia/Black and Caspian Seas; eastern Siberia/East Asia), so further information and data are requested from other parts of its range, especially East Asia.

Under criterion A, an overall decline approaching 30% (typically 20-29%) over 25 years would probably qualify the species for Near Threatened, while a decline of at least 30% over 25 years could make it eligible for uplisting to Vulnerable.


Butcher, G. S. and Niven, D. K. (2007) Combining Data from the Christmas Bird Count and Breeding Bird Survey to Determine the Continental Status and Trends of North American Birds. Ivyland, PA: National Audubon Society.

Skov, H., Heinänen, S., Žydelis, R, Bellebaum, J., Bzoma, S., Dagys, M., Durinck, J., Garthe, S., Grishanov, G., Hario, M., Kieckbusch, J. K., Kube, J., Kuresoo, A., Larsson, K., Luigujoe, L., Meissner, W., Nehls, H. W., Nilsson, L., Petersen, I. K., Roos, M. M., Pihl, S., Sonntag, N., Stock, A. and Stipniece, A. (2011) Waterbird Populations and Pressures in the Baltic Sea. TemaNord 2011: 550. Copenhagen, Denmark: Nordic Council of Ministers.

Wetlands International (2006) Waterbird population estimates. Fourth edition. Wageningen, The Netherlands: Wetlands International.

The following letter was sent by Michael L. Szymanski on behalf of the Central Flyway Council on 30 January 2012: Aythya marila Central Flyway Jan12

The following letter by Jean-Michel DeVink, with support from members of the Canadian Wildlife Service’s Waterfowl Committee, was received on 30 January 2012: Aythya marila DeVink Jan12

The following letter was received on 31 January 2012: Aythya marila Lehikoinen et al. Jan12

The following information was received on 14 February 2012: Greater ScaupStatus 14Feb12 J Barclay

This entry was posted in Americas, Archive, Asia, Europe & Central Asia, North America, Waterbirds. Bookmark the permalink.

7 Responses to Archived 2011-2012 topics: Greater Scaup (Aythya marila): uplist to Near Threatened or Vulnerable?

  1. Ian Burfield says:

    Aythya marila is listed as nationally Near Threatened in the 2011 update of the Red List of the birds of France. [UICN France, MNHN, LPO, SEOF & ONCFS (2011) La Liste rouge des espèces menacées en France – Chapitre Oiseaux de France métropolitaine. Paris, France.

  2. In Finland, Greater Scaup was nationally red listed in 2000 as Vulnerable and in 2010 as Endangered. National population has declined since 1970’es from about 2000 breeding pairs to 1200 breeding pairs by the end of 1990’es (Hario 2007) and about 500 pairs by 2010 ( About 90 % of population breeds on coastal archipelago (Baltic Sea) and tiny amount in Lapland tundra. The trend of Finnish Lapland population is not well understood, but probably declining too. Breeding population was formerly continuous along Finnish coast, but is now highly fragmented and virtually disappeared from Gulf of Finland (occasional breeder only from 2000 onwards). Haldin (in EBCC bird atlas 1997) suspects, that probably the Baltic Sea population do not recieve any more recruite from tundra population for its maintenance. I share this view, but it is not proven however. GS lacks unfortunately population studies.

    In Estonia, GS was nationally red listed in 2008 as Critically Endangered (this was first RedList assessment with IUCN criteria ever in Estonia). Timing of decline is corresponding with the trend in Finland (since 1970’es), and was only about 50 pairs by the end of 1990’es (Lõhmus et al 1998) and 1-10 pairs by 2008 (Elts & al 2009)

    North-Russian population is migrating in autumns along north coast of Estonia. According extensive and comparable monitoring (Ellermaa & al 2010) in autumns 2004 and 2009 at Põõsaspea Cape, observed numbers of passing GS decreased about 20 % (n=34000 and 26600 respectively). At the same time the Tufted Duck Ayhya fuligula with highly similar migration timing and pattern, increased about 35 % (n = 11500 and 15500). The amount of unidentified ducks does not explain the differences. The increase of Tufted Ducks was simultaneously observed 70 km north from Põõsaspea, in Hanko bird station, with annual monitoring (Lehikoinen & al 2008). The trend of GS was unclear in latter location (possibly because of small sample, as GS is rare migrant there).


    Ellermaa, M., Pettay, T. & Könönen, J. 2010: Autumn migration in Põõsaspea Cape in 2009. Hirundo 23:21-46.
    Estonian red list, GS:
    Elts, J. & al 2009: Eesti lindude staatus, pesitsusaegne ja talvine arvukus 2003–2008. – Hirundo 22:3-31.
    Hario, M. 2007: Tiirojen, sotkien, naurulokin ja haahkan kannankehitys rannikoilla 1986–2006. – Linnut-yearbook 2006:36-42.
    Lehikoinen, A. (toim.), Ekroos, J., Jaatinen, K., Lehikoinen, P., Lindén, A., Piha, M., Vattulainen, A. & Vähätalo, A. 2008: Lintukantojen kehitys Hangon lintuasemalla 1979–2007. Bird population trends based on the data of Hanko Bird Observatory (Finland) during 1979–2007. — Tringa 35: 146–209.
    Lõhmus, A. & al 1998: Eesti lindude staatus, pesitsusaegne ja talvine arvukus Hirundo 11: 63-83.
    Rassi, P., Hyvärinen, E., Juslén, A. & Mannerkoski, I. (eds.) 2010: The 2010 Red List of Finnish Species. – Ministry of the Environment
    Finnish Environment Institute.

  3. Jari Kontiokorpi says:

    General from Vyborg, view my comment in Long-tailed Duck.

    Like Velvet Scoter also Greater Scaup use normally more southeastern route than Vyborg Bay is. In Repino near St Petersburg, we saw 1992-2001 in 225 hours in average 156 Greater Scaup/observed hour (N=35000), in Vyborg 1988-2008 in more than 2400 hours in average 13 ind./observed hour. Best day in Repino has been 9200 migrating Greater Scaup in 16.5.1995 and in Vyborg 5000 in 23.5.1995.

    In Vyborg Greater Scaup´s amounts have been quite stable: 1988-94 we counted in average 14 ind./observed hour, in 1995-99 11 and 2000-2008 11 ind. (N=30 000), but also in this case we must remember that the margin of error can be big.

  4. Joe Taylor says:

    The following comments by Dr. Sergei P. Kharitonov were forwarded to us on 30 January 2012:

    Two extensive tundra areas were monitored in the western half of Taimyr: 1) in 2004, 2007, 2010 at the central Taimyr we surveyed near 400 km of the Agapa River streams, from the southernmost Red-breasted Goose colony (70.11N, 86.15E) up to the river mouth (71.26N., 89.13E); 2) in 2000-2007 at the northern Taimyr, Medusa Bay area we monitored 380 sq. km area near the Willem Barents Station (73.23N, 80.32E), including lower streams of the Lemberova, Maximovka and Efremova Rivers and part of the Kara Sea coast.

    1) In the north-west Taimyr, Medusa Bay area only Long-tailed Duck is common staging and breeding bird. Numbers are fluctuating with slight trend to decrease. Years of very low numbers – 2003 and 2007 (flock of several staging birds), usual numbers are – flocks of 10-20 staging birds
    Black Scoter – occasional bird, usually singles very rare can be observed, one time in 2001 flocks of 10 birds was recorded
    Velvet Scoter – occasional bird, singles. In 2003 surprisingly was registered 100 birds, then does not seen in 2004-2007.

    2) Agapa River area – all four duck species are present. Long-tailed duck breeding, it is the most common duck in that area, however numbers ids not high – first hundreds bird per the 400 km river stream.
    Great scoup – numbers is low, several tens of birds per 400 km river stream
    Black Scoter – rear duck, decreasing in numbers over 2004-2010
    Velvet Scoter – rear duck – several tens per 400 km of the Agapa river streams, numbers trend is unclear.

  5. Here are comments for the 2012 IUCN Red List update proposal from the Finnish expert group on birds, which did the evaluation for the last national Red List (2010). Our comments concern four duck species: the Scaup Aythya marila, Long-tailed duck Clangula hyemalis, Velvet scoter Melanitta fusca and Common scoter Melanitta nigra. We have used Finnish breeding censuses (nest counts and breeding atlas) and migration counts as sources of conclusions. We must point out that the migration count analyses are quite harsh, since there was not enough time for detailed analyses. Nevertheless, we believe that the trends that they show indicate real changes in the population sizes, but we should not put too much weight on the exact magnitude of change especially in the uncommon Scaup and Velvet scoter.

    Best wishes,

    Antti Below, Finnish Forest and Park Service, Metsähallitus
    Martti Hario, Finnish Game and Fisheries Institute
    Aleksi Lehikoinen, Finnish Museum of Natural History
    Esa Lehikoinen, University of Turku
    Markku Mikkola-Roos, Finnish Environment Institute
    Jorma Pessa, Centre for Economic Development, Transport and the Environment, Oulu
    Ari Rajasärkkä, Finnish Forest and Park Service, Metsähallitus
    Teemu Lehtiniemi, BirdLife Finland
    Juha Tiainen, Finnish Game and Fisheries Institute
    Jari Valkama, Finnish Museum of Natural History

    Aythya marila (IUCN recommendation NT/VU)
    The Finnish breeding population has been declining since the early 1970s, with an accelerating rate of -47 % in ten years: from 950 pairs in 1998–2002to 500 pairs in 2006–2009. Also the distribution in 10 x 10 km grids has declined between the latest and the previous atlases, from 301 grids in the 1970s–1980s to 140 grids in the 2000s. This reduction applies both to the coastal and the Lappish populations. The breeding population in the Finnish coastal areas has been declining since the 1970s (Väisänen et al. 1998).
    Migration numbers in the eastern Gulf of Finland (Vyborg) have been rather stable during last two decades. Finnish ornithologists have annually monitored migration in Vyborg during spring migration in 1988–2008 (between 5 May and 1 June, altogether 2486 hours; Jari Kontiokorpi, unpublished). In 1988–1994 the density was 14 individuals/observation hour (n = 762 hours), in 1995–1999 density was 11 ind./hour (n = 1061 hours), and in 2000-2008 density was 11 ind./hour (n = 628 hours, total n = 30 000 birds).
    There are also small spring migration data from the northern part of the Gulf of Finland, Söderskär station (for a description of the site, see Hario et al. 2009, Scaup numbers are unpublished) during years 1984–2010, where a few hundreds of birds are seen annually (total n = 6500). The main migration route is situated along the southern part of the Gulf of Finland and thus Söderskär is not on the main migration line. Nevertheless, migration numbers in this spot show a declining trend since mid-1980s.

    Although the breeding population in Finland is small, these rapid changes in distribution and numbers along with the apparent decrease during the migration support the assessment of unfavourable conservation status of the species.

  6. Joe Taylor says:

    The following comments from Dr. Vitaly V. Bianki and Irina A. Kharitonova were forwarded on 30 January 2012:

    Study area: Kandalaksha State Nature Reserve, head of Kandalaksha Bay, the White Sea.

    Aythya marila. Breeding . For the recent decade the numbers decreased. This species used to be common breeder, now it breeds in low numbers.

  7. Andy Symes says:

    Detailed comments on Greater Scaup in North America have been provided by Prof. John Barclay – please see the Word file attached at the base of the original forum topic.

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