Species

Justification
This species has been uplisted to Vulnerable because an apparently drastic decline detected in the wintering population in the Baltic Sea since at least the early 1990s implies that the global population will undergo at least a rapid decline over three generations (1993-2020), even when factoring-in uncertainty regarding the sizes and trends of other populations. Improved knowledge regarding populations outside the Baltic Sea might lead to the species being uplisted to Endangered if the overall rate of decline can be confidently shown to be very rapid.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

Distribution and population
Clangula hyemalis is circumpolar, breeding on the Arctic coasts of North America (Canada, Alaska, USA and Greenland), Europe (Iceland and Norway), and Asia (Russia). It winters at sea further south, as far as the United Kingdom, South Carolina and Washington in the United States, Korea on the Asian Pacific coast, and other areas including the Black Sea and Caspian Sea (del Hoyo et al. 1992). According to monitoring data from the Baltic Sea, where the western Siberian and northern European populations winter, the population there has declined significantly since the early 1990s at least (Hario et al. 2009, Ellermaa et al. 2010, Nilsson and Månsson 2010, Skov et al. 2011). An estimated total of c.4,272,000 individuals was counted there in 1992-1993, falling to c.1,486,000 individuals in 2007-2009, which suggests that a decline of c.65% has occurred over a period of 16 years (Skov et al. 2011). There is no evidence to suggest that the geographical distribution of this population has shifted (Skov et al. 2011, L. Nilsson in litt. 2011, J. Bellebaum in litt. 2012, M. Ellermaa in litt. 2012). The estimation of a real and severe decline is supported by data from the Gulf of Finland flyway, where the numbers observed on migration have fallen dramatically since the early 1990s at least (A. Lehikoinen et al. in litt. 2012). North America holds the second largest population (c.1 million birds [Delany and Scott 2006]). Although Christmas Bird Count (CBC) data indicate an annual population change of -1.9% between 1965 and 2005, across c.70% of the species’s range in North America (Butcher and Niven 2007); however, the reliability of CBC data for monitoring this species has been questioned owing to the species's tendency to winter off-shore (T. Bowman in litt. 2012). There are conflicting results from regional surveys. Indices of abundance obtained during the North American Breeding Waterfowl Survey indicate a steady long-term downward trend between the 1970s and early 1990s, and a stable population since. However, this species is especially poorly monitored because its breeding distribution is largely outside the area covered by breeding waterfowl surveys, and because of its offshore distribution during winter and the lack of comprehensive winter surveys (T. Bowman in litt. 2012). No trend data are available for the third largest population (c.500,000–1,000,000 birds [Delany and Scott 2006]), which breeds in eastern Siberia and winters off eastern Asia. The fourth and smallest population (c.100,000–150,000 birds [Delany and Scott 2006]), which breeds in Greenland and Iceland and winters in the north Atlantic, is poorly monitored and trends are uncertain, although it may have been stable until the 1990s (Delany and Scott 2006). Research on the tundra of eastern European Russia since 1973 suggests that a steep decline may have occurred there (Y. and O. Mineev in litt. 2012).


Population justification
The global population is estimated to number c.6,200,000-6,800,000 individuals (Delany and Scott 2006), while national population sizes have been estimated at c.50-10,000 wintering individuals in Japan and c.100,000-1 million breeding pairs and c.10,000 wintering individuals in Russia (Brazil 2009).

Trend justification
Surveys of the wintering population in the Baltic sea indicate that the species has undergone a precipitous decline there, from c.4,272,000 individuals in 1992-1993 to c.1,486,000 individuals in 2007-2009 (Skov et al. 2011). There is considerable uncertainty over the trends of smaller populations in Europe outside the Baltic sea (300,000 individuals [Delany and Scott 2006]), in Greenland and Iceland (100,000-150,000 individuals [Delany and Scott 2006]), and East Siberia (500,000-1,000,000 [Delany and Scott 2006]), and North America (c.1,000,000 individuals [Delany and Scott 2006]), rendering the estimation of its global trend very difficult. However, the overall rate of decline is likely to approach 50% over three generations (27 years), from 1993 until 2020.

Ecology
Behaviour This species is fully migratory (del Hoyo et al. 1992) although its movements are poorly understood (Scott and Rose 1996). It breeds from late-May onwards (Madge and Burn 1988) in single pairs or loose groups (del Hoyo et al. 1992, Kear 2005b), the males leaving the females soon after the start of incubation (Madge and Burn 1988) (between late-June and early-September) to gather in small flocks for a flightless moulting period (Scott and Rose 1996). Some populations undergo extensive moult migrations of up to 1,000 km, while others moult on waters near the breeding grounds (Madge and Burn 1988). Females moult between early-August and early-October on the breeding grounds (Scott and Rose 1996), often abandoning their young at the start of the moult (the ducklings then gather into large parentless groups) (Johnsgard 1978). The southward autumn migration occurs from September to October after the post-breeding moult (Scott and Rose 1996) and non-breeders may oversummer in the wintering areas (Madge and Burn 1988). Outside of the breeding season the species is highly gregarious (Johnsgard 1978), in winter gathering into large aggregations of perhaps several tens of thousands of individuals to roost or to feed in inshore and offshore waters (del Hoyo et al. 1992). The species regularly dives to depths of 3-10 m when foraging (maximum depth 50-60 m) (Kear 2005b) and is diurnal (Kear 2005b). Habitat Breeding The species breeds on marshy grass tundra in the high Arctic (Flint et al. 1984, del Hoyo et al. 1992), especially where habitat mosaics are formed by hummocks and ridges together with moist depressions (Snow and Perrins 1998), freshwater lakes (del Hoyo et al. 1992, Kear 2005b), bogs (del Hoyo et al. 1992), slow rivers (Madge and Burn 1988, del Hoyo et al. 1992) or pools of standing water (Snow and Perrins 1998). It generally avoids wooded tundra (Johnsgard 1978, Snow and Perrins 1998) but is common among willows or dwarf birch in the arctic-alpine zone (Scandinavia) (Snow and Perrins 1998). The species also breeds on small rocky islands off mainland Arctic coasts and on larger offshore islands, using promontories, deltas (Snow and Perrins 1998), coastal inlets (Madge and Burn 1988, del Hoyo et al. 1992) and islets in fjords (Greenland) (Snow and Perrins 1998). Non-breeding The species winters at sea, generally far offshore (del Hoyo et al. 1992) in waters 10-35 m deep (Scott and Rose 1996), as well as in saline, brackish or fresh estuarine waters (Johnsgard 1978), brackish lagoons (del Hoyo et al. 1992), and inland (very rarely) on large, deep freshwater lakes (del Hoyo et al. 1992). Diet The species showing a preference for marine foods during both the breeding and non-breeding seasons (Johnsgard 1978), its diet consisting predominantly of animal matter (Snow and Perrins 1998) such as crustaceans (del Hoyo et al. 1992) (e.g. amphipods [Kear 2005b] and cladocerans [Johnsgard 1978]), molluscs, other marine invertebrates (e.g. echinoderms, worms) and fish (del Hoyo et al. 1992). The species also takes freshwater insects and insect larvae (del Hoyo et al. 1992) as well as plant material such as algae, grasses, and the seeds and fruits of tundra plants (del Hoyo et al. 1992). Breeding site The nest is a natural depression on dry ground positioned in the open, amongst vegetation (del Hoyo et al. 1992), partially hidden by overhanging boulders (Madge and Burn 1988) or under low shrubs (Johnsgard 1978) (e.g. willows or dwarf birch) (Flint et al. 1984) usually close to water (Madge and Burn 1988). Although it is not a colonial species some pairs may nest in loose groups, and the species may also nest in association with Arctic Terns (Kear 2005b).

Threats
The species is threatened by wetland habitat degradation and loss from petroleum pollution, wetland drainage and peat-extraction (Grishanov 2006). It is also threatened with direct mortality from oil pollution (Gorski et al. 1977, del Hoyo et al. 1992, Kirby et al. 1993), drowning through entanglement in fishing nets (del Hoyo et al. 1992, Kirby et al. 1993) and from hunting on migration routes over certain regions of the Arctic (del Hoyo et al. 1992). The species has previously suffered heavy losses from an outbreak of avian cholera (Friend 2006) and is susceptible to avian influenza (Melville and Shortridge 2006) so may be threatened by future outbreaks of these diseases. There is evidence that the species is experiencing low reproductive success on its Arctic breeding grounds. The results of autumn migration monitoring at various Baltic sites show that juveniles now represent a very low proportion of the population (e.g. Hario et al. 2009, Ellermaa et al. 2010), indicating that insufficient young are being raised to compensate for adult mortality. The breeding success of this (and other) species seems to have declined since the mid-1990s, when the formerly distinctive 3-4 year cycle in the abundance of Arctic rodents collapsed, probably due to climate change. With fewer rodents around, Arctic predators now take a heavier toll on breeding birds every year, instead of only once every 3-4 years. Although the main reason for low breeding productivity seems to be likely connected mainly with skipped breeding, rather than with increased predation pressure, possibly owing to worsened female body condition (A. Kondratyev in litt. 2012). A decline in breeding productivity is supported by unpublished data on the age ratio of gillnet victims in the southern Baltic, which suggest a decline in breeding success by c.75% from prior to 1990 until c. 2000 (J. Bellebaum in litt. 2012). Drastic declines on the tundra of eastern European Russia since 1973 are thought to be connected to the natural cycles of the species, pollution from oil and gas extractions, and pollution from the deposition of nuclear and chemical waste in northern seas (Y. and O. Mineev in litt. 2012). In 2006-2007, on the Hatpudirskaya bay coast (Barents Sea), several thousand dead C. hyemalis were found washed-up on beaches (Y. and O. Mineev in litt. 2012). Utilisation The species is hunted for sport in several countries including Denmark (Bregnballe et al. 2006) and the USA.


Conservation actions underway
Some of the species's habitat is protected. Efforts are on-going to monitor populations of this species in many parts of its range.

Conservation actions proposed
Conduct surveys to monitor the least-known populations in East Asia, improve monitoring in North America, and continue to assess trends in Europe. Carry out research to identify the causes of the decline in the Baltic Sea. React to improved knowledge of threats to the species by implementing actions to mitigate their impacts. Study the causes of reduced breeding productivity.

Related state of the world's birds case studies

• Gillnets pose a significant threat to some seabird populations

References
Johnsgard, P. A. 1978. Ducks, geese and swans of the World. University of Nebraska Press, Lincoln and London.

Flint, V. E.; Boehme, R. L.; Kostin, Y. V.; Kuznetsov, A. A. 1984. A field guide to birds of the USSR. Princeton University Press, Princeton, New Jersey.

Madge, S.; Burn, H. 1988. Wildfowl. Christopher Helm, London.

del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Kirby, J.; Evans, R.; Fox, A. D. 1993. Wintering seaducks in Britain and Ireland: Populations, threats, conservation and research priorities. Aquatic Conservation: Marine and Freshwater Ecosystems 3(2): 105-137.

Scott, D. A.; Rose, P. M. 1996. Atlas of Anatidae populations in Africa and western Eurasia. Wetlands International, Wageningen, Netherlands.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Kear, J. 2005. Ducks, geese and swans volume 2: species accounts (Cairina to Mergus). Oxford University Press, Oxford, U.K.

Gorski, W.; Jakuczun, B.; Nitecki, C.; Petryna, A. 1977. Investigation of oil pollution on the Polish Baltic coast in 1974-1975. Przeglad Zoologiczny 21(1): 20-23.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

Butcher, G. S.; Niven, D. K. 2007. Combining data from the Christmas bird count and the breeding bird survey to determine the continental status and trends of North American birds.

Bregnballe, T.; Noer, H.; Christensen, T. K.; Clausen, P.; Asferg, T.; Fox, A. D.; Delany, S. 2006. Sustainable hunting of migratory waterbirds: the Danish approach. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 854-860. The Stationary Office, Edinburgh, UK.

Friend, M. 2006. Evolving changes in diseases of waterbirds. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 412-417. The Stationary Office, Edinburgh, UK.

Grishanov, D. 2006. Conservation problems of migratory waterfowl and shorebirds and their habitats in the Kaliningrad region of Russia. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 356. The Stationary Office, Edinburgh, UK.

Melville, D. S.; Shortridge, K. F. 2006. Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.

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.; Stipniece, A. 2011. Waterbird Populations and Pressures in the Baltic Sea. Nordic Council of Ministers, Copenhagen.

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.

Ellermaa, M.; Pettay, T.; Könönen, J. 2010. Autumn migration in Põõsaspea Cape in 2009. Hirundo 23(1): 21-46.

Further web sources of information
Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Malpas, L., Taylor, J.

Contributors
Bellebaum, J., Below, A., Bianki, V., Bowman, T., Ellermaa, M., Fefelov, I., Grishanov, G., Hario, M., Kharitonova, I., Kharitonov, S., Kondratyev, A., Kontiokorpi, J., Lehikoinen, A., Lehikoinen, E., Lehtiniemi, T., Mikkola-Roos, M., Mineev, O., Mineev, Y., Nilsson, L., Pessa, J., Pihl, S., Rajasarkka, A., Solovyeva, D., Tiainen, J., Valkama, J.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Clangula hyemalis. Downloaded from http://www.birdlife.org on 25/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

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