email a friend
printable version
Smew Mergellus albellus
BirdLife is updating this factsheet for the 2016 Red List
Please email us with any relevant information

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
Number of locations -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals poor Estimated 2009
Population trend Decreasing Suspected -
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 Resident
Afghanistan Native Extant   Yes    
Albania Native Extant   Yes    
Algeria Vagrant Extant        
Austria Native Extant   Yes    
Azerbaijan Native Extant   Yes    
Belarus Native Extant     Yes Yes
Belgium Native Extant   Yes    
Bosnia and Herzegovina Native Extant        
Bulgaria Native Extant   Yes    
Canada Vagrant 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 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       Yes
Pakistan Native Extant        
Palestinian Authority Territories Vagrant Extant   Yes    
Poland Native Extant   Yes Yes  
Portugal Vagrant Extant        
Romania Native Extant     Yes Yes
Russia Native Extant Yes   Yes Yes
Russia (Asian) Native Extant Yes      
Russia (Central Asian) Native Extant Yes   Yes  
Russia (European) Native Extant       Yes
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 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 Vagrant 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
Iraq Razzaza Lake (Bahr Al Milh) site factsheet
Kazakhstan Chardara Reservoir site factsheet
Kazakhstan Karasuk site factsheet
Kazakhstan Korgalzhyn State Nature Reserve site factsheet
Kazakhstan Sorbulak Lake System site factsheet
Kazakhstan Tentek River Delta site factsheet
Kazakhstan Terenkol Lake 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
Norway Øvre Anárjohka site factsheet
Norway Øvre Pasvik site factsheet
Norway Reisa site factsheet
Norway Vikna 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) Kuznetsky Alatau Zapovednik 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
Serbia Derdap gorge site factsheet
Serbia Labudovo okno 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 Kalmar - Mönsterås site factsheet
Sweden Lake Gammelstadsviken site factsheet
Sweden Lake Skedviken site factsheet
Sweden Lake Tämnaren 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
Food - human - - - Subsistence, National
Pets/display animals, horticulture - - - International

Recommended citation
BirdLife International (2016) Species factsheet: Mergellus albellus. Downloaded from on 22/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 22/10/2016.

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, 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
- 2015 European Red List assessment