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Smew Mergellus albellus

IUCN Red List history

Year Category
2012 Least Concern
2009 Least Concern
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern

Species attributes

Migratory status full migrant Forest dependency Medium
Land mass type   Average mass -


  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 1,900,000 medium
Extent of Occurrence non-breeding (km2) 1,900,000 medium
Number of locations -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals poor Estimated 2009
Population trend Decreasing -
Number of subpopulations - - -
Largest subpopulation - - -
Generation length (yrs) 5.7 - - -
Population justification: The global population is estimated to number > c.130,000 individuals (Wetlands International 2006), while the population in Korea has been estimated at c.50-10,000 wintering individuals (Brazil 2009).
Trend justification: The population is suspected to be much affected by availability of nest sites in suitable habitat. Populations are also subject to hunting pressure during migration and have been affected by pollution from oil spills (del Hoyo et al. 1992).

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage
Afghanistan Native Extant   Yes  
Albania Native Extant   Yes  
Algeria Vagrant Extant      
Austria Native Extant   Yes  
Azerbaijan Native Extant   Yes  
Belarus Native Extant     Yes
Belgium Native Extant   Yes  
Bosnia and Herzegovina Native Extant      
Bulgaria Native Extant   Yes  
Canada Native Extant      
China (mainland) Native Extant      
Croatia Native Extant   Yes  
Cyprus Vagrant Extant      
Czech Republic Native Extant   Yes  
Denmark Native Extant   Yes  
Egypt Native Extant      
Estonia Native Extant   Yes Yes
Finland Native Extant     Yes
France Native Extant   Yes Yes
Germany Native Extant   Yes Yes
Gibraltar (to UK) Vagrant Extant      
Greece Native Extant   Yes  
Hong Kong (China) Vagrant Extant      
Hungary Native Extant   Yes  
Iceland Vagrant Extant      
India Native Extant      
Iran, Islamic Republic of Native Extant   Yes  
Iraq Native Extant   Yes  
Ireland Native Extant   Yes  
Israel Vagrant Extant      
Italy Native Extant   Yes  
Japan Native Extant      
Jordan Vagrant Extant      
Kazakhstan Native Extant Yes    
Kyrgyzstan Native Extant   Yes  
Latvia Native Extant   Yes Yes
Libya Vagrant Extant      
Liechtenstein Native Extant      
Lithuania Native Extant   Yes Yes
Luxembourg Native Extant   Yes  
Macedonia, the former Yugoslav Republic of Native Extant   Yes  
Malta Vagrant Extant      
Moldova Native Extant   Yes  
Mongolia Native Extant      
Montenegro Native Extant   Yes  
Myanmar Vagrant Extant      
Nepal Native Extant      
Netherlands Native Extant   Yes  
North Korea Native Extant      
Norway Native Extant      
Pakistan Native Extant      
Palestinian Authority Territories Vagrant Extant   Yes  
Poland Native Extant   Yes Yes
Portugal Vagrant Extant      
Romania Native Extant     Yes
Russia (Asian) Native Extant Yes    
Russia (Central Asian) Native Extant Yes   Yes
Russia (European) Native Extant      
Saudi Arabia Vagrant Extant   Yes  
Serbia Native Extant   Yes  
Slovakia Native Extant   Yes Yes
Slovenia Native Extant   Yes  
South Korea Native Extant      
Spain Native Extant   Yes  
Sweden Native Extant     Yes
Switzerland Native Extant   Yes  
Syria Native Extant   Yes  
Taiwan (China) Native Extant      
Tajikistan Native Extant      
Tunisia Vagrant Extant      
Turkey Native Extant   Yes  
Turkmenistan Native Extant      
Ukraine Native Extant   Yes Yes
United Kingdom Native Extant   Yes  
USA Native Extant   Yes  
Uzbekistan Native Extant      

Important Bird Areas where this species has triggered the IBA criteria

Country/Territory IBA Name IBA link
Estonia Irbe strait site factsheet
Estonia Lõu bay site factsheet
Estonia Luitemaa site factsheet
Estonia Mouth of the Emajõgi river and Piirissaar island site factsheet
Estonia Väinameri site factsheet
Estonia Võrtsjärv site factsheet
Finland Elimyssalo site factsheet
Finland Käsivarsi fjelds site factsheet
Finland Kemihaara (Vuotos) mires and forests site factsheet
Finland Kitka lake site factsheet
Finland Lemmenjoki-Hammastunturi-Pulju site factsheet
Finland Litokaira site factsheet
Finland Oulanka-Sukerijärvi site factsheet
Finland Oulu region wetlands site factsheet
Finland Pallas and Ylläs fjelds site factsheet
Finland Pomokaira-Koitelaiskaira site factsheet
Finland Porvoonjoki Delta site factsheet
Finland Runkaus-Saariaapa-Tainijärvet site factsheet
Finland Saariselkä and Koilliskaira site factsheet
Finland Sammutinjänkä-Vaijoenjänkä site factsheet
Hungary Hortobágy and Tisza-to site factsheet
Iran, Islamic Republic of Anzali Mordab complex site factsheet
Iran, Islamic Republic of Voshmigir dam site factsheet
Kazakhstan Korgalzhyn State Nature Reserve site factsheet
Kazakhstan Uyalyshalkar Lake System site factsheet
Latvia Irbe strait site factsheet
Latvia Lubans and fish-ponds site factsheet
Lithuania Nemunas delta regional Park site factsheet
Lithuania The northern part of the Curonian Lagoon site factsheet
Luxembourg Haff Réimech site factsheet
Netherlands Gelderse Poort site factsheet
Netherlands IJssel: IJsselkop-Ketelmeer site factsheet
Netherlands Lake IJsselmeer site factsheet
Netherlands Lake Markermeer site factsheet
Netherlands Lepelaarplassen site factsheet
Poland Delta of the Swina river site factsheet
Poland Kamien Lagoon and Dziwna River site factsheet
Poland Lower Odra river valley site factsheet
Poland Puck Bay site factsheet
Poland Slowinska Site site factsheet
Poland Slowinski National Park site factsheet
Poland Szczecin lagoon site factsheet
Poland Vistula Lagoon site factsheet
Romania Argeş reservoir site factsheet
Romania Black Sea site factsheet
Romania Buhuşu reservoir - Bacău - Tătărăşti site factsheet
Romania Cefa fish-ponds and Radvani wood site factsheet
Romania Cursul Dunării - Baziaş - Porţile de Fier site factsheet
Romania Danube Delta site factsheet
Romania Iazurile de pe Văile Ibănesei - Başeului - Podrigăi site factsheet
Romania Iezerul Călăraşi site factsheet
Romania Ilfov reservoir site factsheet
Romania Lacurile Fălticeni site factsheet
Romania Lake Techirghiol site factsheet
Romania Limanu - Herghelia site factsheet
Romania Olt valley site factsheet
Romania Rogojeşti reservoir - Bucecea site factsheet
Romania Stânca lake - Costeşti site factsheet
Russia (Asian) Forty islands site factsheet
Russia (Asian) Lowland swamps in the valley of Tungur and Nenyuga rivers site factsheet
Russia (Central Asian) Basins of the Schuchya and Khadytayakha rivers site factsheet
Russia (Central Asian) Dikoye and Epanchino lakes site factsheet
Russia (Central Asian) Dvuob'ye site factsheet
Russia (Central Asian) Ilmensky zapovednik site factsheet
Russia (Central Asian) Kondo-Alymskaya site factsheet
Russia (Central Asian) Kuznetski Alatau site factsheet
Russia (Central Asian) Lower Ob' site factsheet
Russia (Central Asian) Russkoye lake site factsheet
Russia (Central Asian) Upper streams of Ob' river site factsheet
Russia (European) Adovo-Chugrumski wetland site factsheet
Russia (European) Iremel'ski mountain site factsheet
Russia (European) Kamsko-Bakaldinskiye marshes site factsheet
Russia (European) Kivach Nature Reserve site factsheet
Russia (European) Kuloy river site factsheet
Russia (European) Lapland Biosphere Reserve site factsheet
Russia (European) Ponoiskaya depression site factsheet
Russia (European) Verkhnevisherski mountain site factsheet
Russia (European) Yamantau mountain site factsheet
Russia (European) Yuzhskoe lake-land site factsheet
Slovakia River Danube flood-plain site factsheet
Slovenia River Drava site factsheet
Sweden Bay of Kilsviken site factsheet
Sweden Blekinge Archipelago site factsheet
Sweden Coastal areas of eastern Gotland island site factsheet
Sweden Lake Gammelstadsviken site factsheet
Sweden Lake Skedviken site factsheet
Sweden River Umeälven delta site factsheet
Sweden Sjaunja site factsheet
Sweden Stornäset - Hörningsholm site factsheet
Sweden Strandstuguviken site factsheet
Sweden Taavavuoma site factsheet
Sweden Western part of lake Mälaren site factsheet
Ukraine Kakhovs'ke reservoir (Energodar) site factsheet
Ukraine Molochnyj Liman site factsheet
Ukraine Sasyk lake site factsheet
United Kingdom Dungeness To Pett Levels site factsheet
United Kingdom South-west London Waterbodies site factsheet
Uzbekistan Dengizkul Lake site factsheet
Uzbekistan Karakyr Lakes site factsheet
Uzbekistan Kattakurgan Reservoir site factsheet
Uzbekistan Tudakul and Kuymazar Reservoirs site factsheet

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Boreal major breeding
Marine Coastal/Supratidal Coastal Brackish/Saline Lagoons/Marine Lakes suitable non-breeding
Marine Neritic Estuaries suitable non-breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) major breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) major non-breeding
Wetlands (inland) Permanent Freshwater Marshes/Pools (under 8ha) suitable breeding
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) suitable breeding
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) suitable non-breeding
Altitude 0 - 0 m Occasional altitudinal limits  

Threats & impact

Threat (level 1) Threat (level 2) Impact and Stresses
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Indirect ecosystem effects, Ecosystem degradation


Purpose Primary form used Life stage used Source Scale Level Timing
Food (human) Whole Adults and juveniles Wild Subsistence, National Non-trivial Recent
Pets Whole Adults and juveniles Wild International Non-trivial Recent

Recommended citation
BirdLife International (2014) Species factsheet: Mergellus albellus. Downloaded from on 13/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 13/07/2014.

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.

Key facts
Current IUCN Red List category Least Concern
Family Anatidae (Ducks, geese and swans)
Species name author (Linnaeus, 1758)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,900,000 km2
Country endemic? No
Links to further information
- Summary information on this species