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Red-breasted Merganser Mergus serrator

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 Does not normally occur in forest
Land mass type   Average mass -


  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 4,090,000 medium
Extent of Occurrence non-breeding (km2) 4,090,000 medium
Number of locations -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals poor Estimated 2009
Population trend Stable -
Number of subpopulations - - -
Largest subpopulation - - -
Generation length (yrs) 7.3 - - -
Population justification: The global population is estimated to number c.510,000-610,000 individuals (Wetlands International 2006). National population estimates include: c.100-10,000 breeding pairs and c.50-1,000 wintering individuals in China; <c.50 individuals on migration and <c.50 wintering individuals in Taiwan; c.50-10,000 wintering individuals in Korea and c.100,000-1 million breeding pairs and c.1,000-10,000 wintering individuals in Russia (Brazil 2009).
Trend justification: The overall population trend is stable, although some populations have unknown trends (Wetlands International 2006). This species has had stable population trends over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage
Afghanistan Vagrant Extant      
Albania Native Extant   Yes  
Algeria Vagrant Extant      
Armenia Native Extant Yes    
Austria Native Extant   Yes  
Azerbaijan Native Extant   Yes  
Bahamas Native Extant      
Bahrain Vagrant Extant   Yes  
Belarus Native Extant     Yes
Belgium Native Extant   Yes  
Belize Vagrant Extant      
Bermuda (to UK) Native Extant      
Bosnia and Herzegovina Native Extant      
Bulgaria Native Extant   Yes  
Canada Native Extant Yes   Yes
Cayman Islands (to UK) Vagrant Extant      
China (mainland) Native Extant      
Croatia Native Extant   Yes  
Cuba Native Extant      
Cyprus Native Extant   Yes  
Czech Republic Native Extant   Yes  
Denmark Native Extant     Yes
Dominican Republic Vagrant Extant     Yes
Egypt Native Extant      
Estonia Native Extant     Yes
Faroe Islands (to Denmark) Native Extant      
Finland Native Extant     Yes
France Native Extant     Yes
Germany Native Extant     Yes
Gibraltar (to UK) Vagrant Extant      
Greece Native Extant      
Greenland (to Denmark) Native Extant      
Haiti Vagrant Extant      
Hungary Native Extant   Yes  
Iceland Native Extant      
India Vagrant Extant      
Iran, Islamic Republic of Native Extant   Yes  
Iraq Native Extant      
Ireland Native Extant      
Israel Native Extant      
Italy Native Extant   Yes  
Japan Native Extant      
Jordan Vagrant Extant      
Kazakhstan Native Extant Yes    
Kuwait Vagrant Extant   Yes  
Kyrgyzstan Native Extant      
Latvia Native Extant      
Lebanon Vagrant Extant   Yes  
Libya Native Extant      
Liechtenstein Native Extant      
Lithuania Native Extant     Yes
Luxembourg Vagrant Extant      
Macedonia, the former Yugoslav Republic of Native Extant      
Malta Native Extant      
Mexico Native Extant      
Moldova Native Extant   Yes  
Mongolia Vagrant Extant      
Montenegro Native Extant   Yes  
Morocco Native Extant      
Nepal Vagrant Extant      
Netherlands Native Extant      
North Korea Native Extant      
Northern Mariana Islands (to USA) Vagrant Extant      
Norway Native Extant     Yes
Oman Vagrant Extant   Yes  
Pakistan Native Extant      
Palestinian Authority Territories Vagrant Extant   Yes  
Philippines Unknown Extant      
Poland Native Extant     Yes
Portugal Native Extant   Yes  
Puerto Rico (to USA) Vagrant Extant      
Romania Native Extant   Yes Yes
Russia (Asian) Native Extant Yes    
Russia (Central Asian) Native Extant Yes   Yes
Russia (European) Native Extant Yes   Yes
Saudi Arabia Vagrant Extant   Yes  
Serbia Native Extant   Yes  
Slovakia Native Extant   Yes  
Slovenia Native Extant   Yes  
South Korea Native Extant      
Spain Native Extant   Yes  
St Pierre and Miquelon (to France) Native Extant      
Svalbard and Jan Mayen Islands (to Norway) Vagrant Extant      
Sweden Native Extant     Yes
Switzerland Native Extant      
Syria Vagrant Extant   Yes  
Taiwan (China) Native Extant      
Tunisia Native Extant      
Turkey Native Extant   Yes  
Turkmenistan Native Extant      
Turks and Caicos Islands (to UK) Native Extant      
Ukraine Native Extant     Yes
United Arab Emirates Vagrant Extant   Yes  
United Kingdom Native Extant      
USA Native Extant Yes    
Uzbekistan Native Extant      
Virgin Islands (to USA) Vagrant Extant      

Important Bird Areas where this species has triggered the IBA criteria

Country/Territory IBA Name IBA link
Canada Long Point Peninsula and Marshes site factsheet
Canada Point Pelee site factsheet
Denmark Eastern part of Vejlerne site factsheet
Denmark Hyllekrog-Rødsand and Fehmarn Belt site factsheet
Denmark Rønne Banke site factsheet
Denmark Smålandsfarvandet site factsheet
Denmark Sydfynske Ø-hav site factsheet
Denmark Vestamager and adjacent sea area site factsheet
Finland Kokkola and Kälviä archipelago site factsheet
Finland Merenkurkku archipelago site factsheet
Finland Oulu region wetlands site factsheet
Finland Rahja archipelago site factsheet
France Golfe du Morbihan et Etier de Penerf site factsheet
Greenland (to Denmark) Ikkattoq fjord and islands site factsheet
Iran, Islamic Republic of Gomishan marshes and Turkoman steppes site factsheet
Iran, Islamic Republic of Miankaleh Peninsula and Gorgan Bay site factsheet
Latvia Gulf of Riga, west coast site factsheet
Netherlands Grevelingen site factsheet
Netherlands Lake Veersemeer site factsheet
Norway Froan site factsheet
Norway Ørland wetland system site factsheet
Norway Smøla archipelago site factsheet
Norway Tanamunningen site factsheet
Poland Pomeranian bay site factsheet
Russia (Asian) Forty islands site factsheet
Russia (Asian) Kunashir island site factsheet
Russia (Asian) Kuril islands (between Urup and Paramushir) site factsheet
Russia (Asian) Nevskoye lake site factsheet
Russia (Asian) North-east Sakhalin lagoons site factsheet
Russia (Asian) Tyk and Viakhtu bays site factsheet
Russia (Central Asian) Basins of the Schuchya and Khadytayakha rivers site factsheet
Russia (Central Asian) Dvuob'ye site factsheet
Russia (Central Asian) Kuznetski Alatau site factsheet
Russia (Central Asian) Lower Ob' site factsheet
Russia (Central Asian) Upper and Middle Yuribey site factsheet
Russia (Central Asian) Upper streams of Ob' river site factsheet
Russia (European) Berezovye islands of Vyborg Bay site factsheet
Russia (European) Kuloy river site factsheet
Sweden Bay of Kungsbackafjorden site factsheet
Sweden Outer Stockholm archipelago site factsheet
United Kingdom Carlingford Lough site factsheet
United Kingdom Moray Basin, Firths and Bays site factsheet

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Marine Coastal/Supratidal Coastal Brackish/Saline Lagoons/Marine Lakes suitable non-breeding
Marine Neritic Estuaries suitable non-breeding
Marine Neritic Macroalgal/Kelp suitable non-breeding
Marine Neritic Seagrass (Submerged) suitable non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable non-breeding
Marine Neritic Subtidal Sandy suitable non-breeding
Marine Neritic Subtidal Sandy-Mud suitable non-breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) major breeding
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) major 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
Sport Whole Adults and juveniles Wild Subsistence, National Non-trivial Recent

Recommended citation
BirdLife International (2014) Species factsheet: Mergus serrator. Downloaded from on 17/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 17/04/2014.

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 Stable
Distribution size (breeding/resident) 4,090,000 km2
Country endemic? No
Links to further information
- Summary information on this species