Smew
Mergellus albellus (Linnaeus, 1758)
SY
SMEW.
2200
Family: Anseriformes > Anatidae
Crisp black and white-coloured male and red-headed female Smew are winter visitors to UK lakes, reservoirs and coastal waters.
Smew begin arriving in the UK during October but have a prolonged period of movements throughout the winter and birds can arrive at any time in response to freezing conditions on their Continental wintering areas. The south-east of the UK receives the lion’s share but a few individuals do make it further west. Records are scarce in Scotland, Wales and Ireland.
The numbers of Smew wintering in the UK has fallen in recent years, possibly in response to milder conditions on the Continent, which maintain waterbodies free of ice for longer.
Select a topic for more facts and statistics about the Smew
Identification
Smew identification is usually straightforward.
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Population size and trends and patterns of distribution based on BTO surveys and atlases with data collected by BTO volunteers.
CONSERVATION STATUS
This species can be found on the following statutory and conservation listings and schedules.
| UK Birds of Conservation Concern | Red listed |
| Species of European Conservation Concern | Least Concern |
| IUCN Red List of Threatened Species (global) |
Least Concern 
|
| Schedule 1 license required (to disturb) | No |
| Birds Directive Annex 1 | Yes |
|
Listed on the Annexes of
|
WBD(I), Bern(III), Bonn(II), AEWA |
POPULATION SIZE
| UK (winter) | 125 (2012-17) |
| BOU Category | A |
|
First Record
|
1666 |
POPULATION CHANGE
| UK winter population |
-85% decrease (1995/96 to 2020/21) |
DISTRIBUTION
The Smew's winter distribution map shows that they were recorded widely across lowland England, Scotland and Wales during 2007–11. There were also records from the Isle of Man and the Channel Islands, where they are scarce winter visitors.
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Britain and Ireland Breeding Distribution 2008-2011.
More from the Atlas Mapstore. -
Britain and Ireland Winter Distribution 2008-2011.
More from the Atlas Mapstore.
Occupied 10-km squares in UK
| No. occupied in winter | 405 |
| % occupied in winter | 13 |
European Distribution Map
DISTRIBUTION CHANGE
More from the Atlas Mapstore.
| % change in range in winter (1981–84 to 2007–11) | +69.9% |
SEASONALITY
Smews are localised winter visitors, most often recorded in late winter when cold weather on the continent can push birds into southern Britain.
Movement
Information about movement and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.
RINGING RECOVERIES
View a summary of recoveries in the Online Ringing Report.
Biology
Lifecycle and body size information about Smew, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.
PRODUCTIVITY & NESTING
|
Number of Broods
|
1 |
|
Egg Size
|
53×38 mm Weight = 42 g (of which 9% is shell) |
BIOMETRICS
Sample sizes are too small to report Biometrics for this species.
Feather measurements and photos on featherbase
CODES & CLASSIFICATION
|
Field Codes
|
2-letter: SY | 5-letter code: SMEW. | Euring: 2200 |
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Links to more information from ConservationEvidence.com
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