Species Profile
Smew
Mergellus albellus
Smew
Quick Facts
Conservation
LCLeast ConcernAlso known as: White Nun
Gallery
Appearance
The Smew is a small, distinctive diving duck. Males are primarily white with intricate black markings, including a black eye patch and fine lines on the sides. They have a crested head and a thin, serrated grey bill.
Females are predominantly grey with a chestnut-brown head and white cheek patch. Both sexes have grey legs and feet and a vague crest on the back of their head.
Non-breeding males moult into an eclipse plumage that is fairly similar to the colouring of a female but retains their black backs and white wing patches. Juveniles resemble females but with duller plumage.
Identification & Characteristics
Male Colors
- Primary
- White
- Secondary
- Grey
- Beak
- Grey
- Legs
- Grey
Female Colors
- Primary
- Brown
- Secondary
- White
- Beak
- Grey
- Legs
- Grey
Female Markings
Chestnut-brown head with white cheek patch
Attributes
Understanding Attributes
Rated 0–100 based on research and observation. A score of 50 is average across all bird species. These attributes are relative and don't necessarily indicate superiority.
Habitat & Distribution
Smews breed in northern taiga forests across Scandinavia and Russia, nesting near freshwater lakes and rivers. During winter, they migrate to coastal areas and inland waters of central and southern Europe, including the UK, as well as parts of Asia.
In the UK, Smews are winter visitors found in reservoirs, lakes, and estuaries. They are more common in eastern and southern England, with smaller numbers reaching Scotland and Wales. The most common sightings are usually from Lincolnshire to the Severn estuary.
Distribution
Where to See This Bird
Explore regional guides for locations where this bird has been recorded.
Diet
Smews primarily feed on small fish, aquatic insects, amphibians, and crustaceans. They are skilled underwater hunters, using their serrated bills to grasp slippery prey. During the breeding season, they may also consume some plant material, including seeds and aquatic vegetation.
In winter, more fish, including salmon, trout, gudgeon, herring, eels, and carp, are caught, depending on location, with both freshwater and saltwater species eaten.
Despite their small size, they are able to catch relatively large fish, with eels up to 29 cm not posing much of a problem!
Behaviour
Smews are agile swimmers and excellent divers, often submerging for 15-30 seconds while foraging. They are typically seen in small flocks during winter, sometimes mixing with other diving ducks.
During the breeding season, males perform elaborate courtship displays, including head-throws and backward kicks on the water surface.
Calls & Sounds
Smews are generally quiet birds. Males produce a soft, rattling 'krrr' during courtship displays. Females have a harsh, croaking call, described as a repeated 'kek-kek-kek'. When alarmed, both sexes may emit a sharp, grating sound.
Nesting & Breeding
Smews form monogamous pairs during the breeding season, which typically begins in May. Males court females with elaborate displays, including head-bobbing and water-splashing.
Females lay 6-9 cream-coloured eggs in tree cavities or nest boxes, often near water. The nest is lined with down feathers plucked from the female's breast.
Incubation lasts about 28 days, carried out solely by the female. Ducklings leave the nest within 24 hours of hatching and are capable of diving and feeding themselves, though they remain with the female for protection.
The male initially stands guard nearby, but as the incubation period progresses, leaves the breeding grounds and plays no active part in raising the ducklings once they hatch.
Conservation
While currently listed as Least Concern, Smews face threats from habitat loss and degradation of breeding areas. Climate change may also impact their distribution and migration patterns.
Conservation efforts focus on protecting wetland habitats and monitoring population trends across their range.
Birdwatching Tips
- Look for Smews on lakes, reservoirs, and coastal bays during winter months
- Scan for the striking white plumage of males, which stands out among other waterfowl
- Observe their diving behaviour, as they frequently submerge in search of food
- In the UK, check well-known wintering sites like Dungeness in Kent or Rutland Water
Did You Know?
- The Smew is the only member of its genus, Mergellus.
- Their serrated bill is specially adapted for catching and holding slippery fish.
- The name 'Smew' is thought to derive from an old English word meaning 'smooth'.
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