Archived 2011-2012 topics: Taxonomic changes in the genus Melanitta, part I: suggestion to list M. nigra as Vulnerable and request for information on M. americana

Initial deadline for comments: 31 January 2012.

BirdLife species factsheet for Black Scoter (prior to the taxonomic change)

Black Scoter Melanitta nigra has been split into M. nigra and M. americana following a review of recent literature (Livezey 1995, Garner et al. 2004, Sangster et al. 2005, Collinson et al. 2006, AOU 2010) and museum specimens by the BirdLife Taxonomic Working Group. Prior to this taxonomic change, the polytypic species M. nigra was listed as being of Least Concern on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria.

Following the taxonomic change, both species are still regarded as having extremely large ranges and hence do 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). Their population sizes are also large (>530,000 individuals; Wetlands International 2006), and hence do 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, there was little evidence to suggest that populations of either taxa were declining 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).

M. nigra
There is now evidence of a rapid decline in the population of M. nigra (Skov et al. 2011), which breeds in western Siberia, Scandinavia, Iceland, Scotland and Ireland, and winters in the Baltic Sea and east Atlantic south to Mauritania (Wetlands International 2006). An analysis of the population trend in the Baltic Sea suggests that a decline of 47.4% occurred between 1988-1993, when a total of c.783,000 birds wintered there, and 2007-2009, when c.412,000 birds were counted (Skov et al. 2011). Extrapolation of these data suggests that this is equivalent to a decline of c.55% over three generations (23 years, based on a generation length of c.7.5 years; BirdLife International unpubl. data).

The Baltic Sea is (or at least was) the most important wintering area in the world for this species. The 783,000 birds recorded there in 1992-1993 represented just under half of the latest (but obviously now outdated) global population estimate of c.1,600,000 birds (Wetlands International 2006). The decline detected in the Baltic Sea population therefore has global significance. The current trend of the birds that winter outside the Baltic is largely unknown, but there is some evidence that these may also be declining, e.g. in the Netherlands (Hornman et al. 2011). The proportion of birds wintering in the Baltic Sea is believed to be linked to the breeding success of birds in Russia (Durinck et al. 1994 in Skov et al. 2011).

It is possible that the lower numbers recorded in the Baltic (and possibly elsewhere in north-western Europe) relate not to a population decline, but to changes in the species’s winter distribution. In recent decades, many waterfowl species have responded to global climate change by ‘short-stopping’, i.e. taking advantage of warmer conditions to winter closer to northern breeding areas than was previously possible. M. nigra may have been affected by this phenomenon, and there is some evidence for a slight northwards shift in the species’s distribution within the Baltic (Skov et al. 2011). However, this is not capable of explaining the whereabouts of the c.360,000 birds ‘missing’ from the Baltic. It is possible that some birds may now be wintering in the White Sea or Barents Sea off north-western Russia, but there is no evidence for this.

If the decline in the Baltic also applies to the rest of the species’s population, then globally it may be declining at a rate of more than 40% over three generations, which would qualify the species for uplisting to Vulnerable under criterion A. To permit a more comprehensive assessment, further and more recent information on the size and trend of the species’s population is requested for all parts of its range, but particularly from those countries along the North Sea and Atlantic coasts, which have held large wintering populations in the past.

M. americana
This species is thought to be declining in western Alaska and to be stable on the Arctic coastal plain (per Sea Duck Joint Venture 2003). Numbers also appear to be declining in the Atlantic flyway, whereas no statistically significant population trend is apparent in the results of a fixed-wing aerial survey covering the Atlantic coast for the period 1991-1999 (Sea Duck Joint Venture 2003). Data from the US Fish and Wildlife Service–Canadian Wildlife Service breeding waterfowl survey indicate that the combined population of all three scoter species along survey transects in the western boreal forest may have declined by as much as 75% since the 1950s. Mid-winter inventory data do not indicate any trends on the Pacific coast and only weakly show a decline on the Atlantic coast. However, these surveys are said to track scoter populations poorly and all three species are combined in one count (Sea Duck Joint Venture 2003). An analysis of Christmas Bird Count data overall indicates an annual change of -1.26% between 1965-1966 and 2005-2006 across about half of the species’s range in North America (Butcher and Niven 2007), equating to a 40-year decline of c.50%, and thus suggestive of a c.32% decline over the last three generations, provisionally assumed to be 23 years, based on a generation length of c.7.5 years (BirdLife International unpubl. data), and an exponential trend.

However, trends are apparently unknown in far north-east Asia, where the species occurs east of Lena and numbers an estimated 300,000-500,000 birds or 12-24% of the estimated global population (see Wetlands International 2006), thus more information is required.

Further information is requested on population trends in these two newly-split species and comments are invited on whether the population of M. nigra is likely to have declined at a rate equivalent to at least 30% over the past three generations, and thus if it qualifies for listing as at least Vulnerable under criterion A. Under the same criterion a decline of at least 50% over three generations would qualify the species for Endangered, whereas a decline approaching 30% (typically 20-29%) would qualify the species for Near Threatened. Likewise, comments are invited on the population trend of M. americana, especially in East Asia.

References:

American Ornithologists’ Union (2010) Fifty-first Supplement to the American Ornithologists’ Union Check-list of North American Birds. Auk 127: 726-744.

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.

Collinson, M., Parkin, D. T., Knox, A. G., Sangster, G. and Helbig, A. J. (2006) Species limits within the genus Melanitta, the scoters. British Birds 99: 183-201.

Garner, M., Lewington, I. and Rosenberg, G. (2004) Stejneger’s Scoter in the Western Palearctic and North America. Birding World 17: 337-347.

Holt, C. A., Austin, G. E., Calbrade, N. A., Mellan, H. J., Mitchell, C., Stroud, D. A., Wotton, S. R. and Musgrove, A. J. (2011) Waterbirds in the UK 2009/10: The Wetland Bird Survey. Thetford, UK: BTO/RSPB/JNCC.

Hornman, M., Hustings, F., Koffijberg, K., van Winden, E., SOVON Ganzen-en Zwanenwerk-groep and Soldaat, L. (2011) Watervogels in Nederland in 2008/2009. SOVON-monitoringrapport 2011/03, Waterdienst-rapport BM 10.24. SOVON Vogelonderzoek Nederland, Nijmegen.

Livezey, B. C. (1995) Phylogeny and Evolutionary Ecology of Modern Seaducks (Anatidae: Mergini). Condor 97: 233-255.

Sangster, G., Collinson, J. M., Helbig, A. J., Knox, A. G. and Parkin, D. T. (2005) Taxonomic recommendations for British birds: third report. Ibis 147: 821-826.

Sea Duck Joint Venture (2003) Species status report. http://www.seaduckjv.org/meetseaduck/species_status_summary.pdf

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 received on 31 January 2012:Melanitta nigra Lehikoinen et al. Jan12

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11 Responses to Archived 2011-2012 topics: Taxonomic changes in the genus Melanitta, part I: suggestion to list M. nigra as Vulnerable and request for information on M. americana

  1. Time series from Finland and Estonia highly disagree with SOWBAS report. Common Scoter (CS) is only arctic duck with no decreasing trend 1995 onwards. CS is consentrated in Gulf of Finland when migrating to/from North-Russia. Gulf of Finland is probably best monitored flyway in the world.

    In autumn 2009; 0,8 million Common Scoters was counted passing to SW in Põõsaspea Cape, NW Estonia. 99 % of those were adults (Ellermaa & al 2010). Comparision between 2004 and 2009 shows rather increasing trend. Time series from Hanko Bird Observatory shows long time increase in migrating CS population, but from 1995 onwards rather stable population (Lehikoinen & al 2008).

    Additionally BirdLife Finlands database (www.tiira.fi) includes 28000 observations (8,75 million ind.) of Common Scoters during 1995-2011, made by birdwatchers. Although there is bias towards observations submitted after 2005, there is no sign of any decreas of the species (eg. average CS number per observation has no clear trend during 1995-2011). Best migration (= biggest number passing in certain point) was observed in spring 2011. When calibrating the number of CS with number on Long-tailed Ducks, the abundance of CS:LTD was 1:3 during spring migration at Gulf of Finland (also according Pettay 1996 earlier in 1980′es). During last few years, it has been 3:1 in advantage of CS.

    Finnish breeding population of CS does not show decreas neither. According IBA-monitoring, numbers have remained same or even slightly increased since 1990′es (BirdLife Finland, unpublished).

    The very controversial results of SOWBAS are hard to understand. Maybe the relocation of wintering birds has happened between North and Baltic Sea, as CS has traditionally overwintered on both seas and has been numerous only in Danish straits at Baltic Sea side – on the border of those seas. CS has not been neither is numerous in northern Baltic Sea in winters.

    References
    Ellermaa, M., Pettay, T. & Könönen, J. 2010: Autumn migration in Põõsaspea Cape in 2009. Hirundo 23:21-46.

    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.

    Pettay, T. 1996: Kevätarktika. – Ympäristönsuojelulautakunta tiedottaa 29/96, Porvoon maalaiskunta. 82 lk.

  2. For M. nigra it might be good to confirm that there was no Westward shift from the Baltic to the North Sea e.g. off Denmark. As in other seaducks there is only very weak evidence for Northward shifts large enough to explain the observed decline in the baltic.

  3. Nial Moores says:

    Asian Waterbird Census data would most likely provide the most-informed insights into the distribution and abundance of American Scoter M. americana overwintering in East Asia.

    Within the Republic of Korea (ROK), there are no robust, long-term datasets which can be used to identify national population trends. However, an analysis of soft data contained within historical literature (Moores 2011) suggests that the species has declined substantially at least since the time of Gore & Won (1971), which described the species as an “Abundant winter visitor off the east and south coasts; rare on the west coast”. During the present century, the species by contrast appears to be scarce and localised. Increasing coverage of suitable habitat in the ROK during the land-based midwinter bird census (conducted under the auspices of the Ministry of Environment since 1999) found a total of only 41 American Scoter in 2000, and 21 in 2010 (MOE 2000, 2010), despite the increased number of sites visited and the improvement in optics and observer experience in the latter compared to the earlier year. The species is perhaps no longer regular on the south coast, and while it was present in small flocks south to 35°N along the east coast in 2000/2001 (when probably >1000 overwintered), by 2009-2011 it seems to be regular only close to or north of 38°N, with <300 found during search of several east coast bays that formerly supported the species (Birds Korea unpublished data). In the ROK part of the Yellow Sea, including along the west coast, the species appears also to be highly localised, with most records from close to 37°N, within 5km of land. Highest counts made during a total of 150 journeys on high-speed vessels of opportunity along three transects between 2000 and 2010, were of only 16 along the northern transect (north of 37°N), zero along the central transect (close to 35°N) and 12 along the southern transect (34°N) (Moores 2011). However, there has still been no ornithological survey of most of the Yellow Sea. In sum, while data are poor an ongoing decline in the ROK at the national level in American Scoter can be suggested; as can a northwards contraction of range. There appears to be no evidence yet to support earlier suggestions that large numbers of the species might overwinter in the Yellow Sea.

    References
    Gore, M. & Won P-O. 1971. The Birds of Korea. Published by the Royal Asiatic Society.
    Ministry of Environment (MOE). 2000, 2010. Winter Bird Census (in Korean).
    Moores, N. 2011. The Distribution, Abundance and Conservation of the Avian Biodiversity of Yellow Sea habitats in the Republic of Korea. Doctoral thesis, University of Newcastle, Australia.

  4. M. Nigra in Sweden

    The breeding population of M.Nigra has a positive or stable population trend in Sweden during the last 30 year period (Ottval et. al. 2009). A late survey, including transects covering most of north Sweden, indicate that breeding numbers has increased in Sweden (Nilsson&Nilsson 2011).This late work compared data collected in 1972-1975 with a recount in 2009. In a coming publication with analysis of long term breeding surveys with annual counts in northern Sweden (Ammarnäs, LUVRE-area) show high yearly variation but with a stable long term trend (Green pers. com. 2011).

    Note that none of these works can find any negative trend for breeding M.nigra populations in Sweden.

    Decreasing numbers in winter population in the Baltic bassin can not be explained with an overall decrease in breeding numbers only. Consequently, a change in winter distribution is likely to have happened. A alternative explonation can be that something goes wrong in the more eastern populations i.e. Russian breeding grounds.

    Green M. 2011. Personal communication with M.Green Common Bird Survey Lund University

    Ottvall R., Edeneius L., Elmberg J., Engström H., Green M., Holmqvist N., Lindström Å., Pärt T & Tjernberg M. 2009. Population trends of the birds. Ornis Svecica 19: 117-192.

    Nilsson J & Nilsson L. 2011. Kraftig ökning av antalet sjöorrar i fjällen. Vår fågelvärld. Birdlife Sweden. (Manuscript for english spoken journal is being processed)

  5. Jari Kontiokorpi says:

    General from Vyborg, view my comment in Long-tailed Duck.
    http://www.birdlife.org/globally-threatened-bird-forums/2011/11/long-tailed-duck-clangula-hyemalis-uplist-to-endangered/

    Common Scoter is another mass species in Vyborg, now more numerous than Long-tailed Duck. Best spring was 1999, when we counted 530 000 Common Scoters, best day 23.5.1996, 296 000 ind.

    Common Scoter´s number´s have been stable in Vyborg: in 1988-94 we counted in average 1583 ind./observed hour, in 1995-99 1457 and 2000-2008 1486 ind. (N=3,7 million).

  6. 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.

  7. We don’t observe any great declining of Greater Scaup, Common and Velvet Scooter in easteuropen tundra and in the Komi Republic. Since 1973 there were interannual fluctuation in number and breeding density appropriate to these species. Probably, declining of Common and Velvet Scooter number occured in Western Siberia. These species are numerous migrants in some areas of the Barents Sea and it is possible to clarify situation by direct observation of migration of Common and Velvet Scooter on the Barents Sea coast.

  8. 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

    Melanitta nigra (IUCN recommendation VU)
    The minor Finnish breeding population (1000–2000 pairs in the north) has been stable and possibly slightly expanding. The amount of grid cells was 261 in the atlases of 1970-80s and 330 cells in the latest atlas of 2000s.
    Migration numbers in Söderskär, northern part of the Gulf of Finland, increased from the 1970s till to the 1990s and were stable since then (see Hario et al. 2009). Like for the Long-tailed ducks, the Söderskär station is situated in the centre of the flyway, and the annual migration numbers have been around 350 000 birds/year in 2000s.
    Migration numbers in the eastern Gulf of Finland (Vyborg) have also been stable during last two decades. Finnish ornithologists have annually monitored migration in Vyborg during the spring migration in 1988–2008 (between 5 May and 1 June, altogether 2486 hours; Jari Kontiokorpi, unpublished). In 1988–1994 the density was 1583 individuals/observation hour (n = 762 hours), in 1995–1999 1457 ind./hour (n = 1061 hours), and in 2000–2008 was 1486 ind./hour (n = 628 hours, total n = 3 700 000 birds).
    Neither the Finnish nor the Russian data support a decline either in the breeding areas or along the migration flyway and these data are thus in contrast with the recommended Vulnerable classification.

    References:
    Hario, M., Rintala, J. & Nordenswan, G. 2009: Dynamics of wintering long-tailed ducks in the Baltic Sea – the connection with lemming cycles, oil disasters, and hunting. Suomen Riista 55:83-96. (In Finnish with English summary).
    Valkama, J., Vepsäläinen, V. & Lehikoinen, A. 2011: The Third Finnish Breeding Bird Atlas. – Finnish Museum of Natural History and Ministry of Environment. http://atlas3.lintuatlas.fi/results/species/common%20scoter

  9. Joe Taylor says:

    The following comments by 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.

    Melanitta nigra. Moulting. The numbers of moulting birds decreased considerably.

  10. Mark Hancock says:

    re. Common Scoter M. nigra in UK:

    The small British breeding population of common scoters declined by about half, between national surveys in 1995 (Underhill et al. 1998) and 2007 (manuscript in preparation), now numbering approximately 50 breeding females. A 3-year research study of breeding ecology of common scoters in Scotland is currently underway – overview at:

    http://www.rspb.org.uk/ourwork/projects/details/239777-the-ecology-of-breeding-common-scoters

    Winter counts of a wide range of wetland birds in Britain includes some data on wintering common scoters in British waters:

    http://www.bto.org/volunteer-surveys/webs/publications/wituk-200910

    The most recent winter analysed, 2009/10, appears to show common scoter numbers somewhat or well above five-year mean peaks (depending on site), which might be linked to birds moving into British waters from areas further east, during severe weather.

    Underhill, MC, Gittings, T, Callaghan, DA, Hughes, B, Kirby, JS, Delany, S (1998) Status and distribution of breeding common scoters Melanitta nigra in Britain and Ireland in 1995. Bird Study 45: 146-156.

  11. Tim Bowman (U.S. Fish and Wildlife Service) has provided the following information:

    In North America, there are two allopatric populations of black scoter – one that breeds in western Alaska and winters along the Pacific coast, and one the breeds in eastern Canada including the boreal forests of east-central Canada and winters along the Atlantic coast. There is no interchange between these populations.
    Long-term data derived from the North American Breeding Waterfowl Survey suggest that scoters in the tundra strata, where black scoters predominate, declined from the 1970s to about year 2000. Estimates from a new survey indicated that the breeding population in western Alaska is currently about 160,000 birds and appears to have increased slightly since the survey was initiated in 2004 (R. Stehn, USFWS, unpublished).
    In eastern North America, the population is estimated at about 250,000 birds, but there is little information on trends due to lack of comprehensive surveys and combining scoters into a single group, which precludes single-species assessments. Migration counts at Avalon, New Jersey, which track an unknown but probably high proportion of the population, indicate a stable or increasing trend in “dark-winged” scoters (e.g., blacks and surfs) through 2004 (more recent data requested).
    No reliable (long term, large scale) winter surveys of sea ducks have been conducted on either the Pacific or Atlantic coasts, or Great Lakes, that enable analysis of trends for wintering populations.
    Christmas Bird Count data for scoters are probably unreliable because these species occur largely offshore where a large proportion may not be seen by shore-based observers, so those data should be viewed with caution.
    Because both North American subpopulations of black scoter are widespread and abundant, and do not meet the criteria for Critically Endangered, Endangered, Vulnerable, or Near Threatened, we recommend it be listed as Least Concern.

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