# UKBirds

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## Smew

### Mergellus albellus

The Smew is a small duck, which is somewhat intermediate between the typical mergansers (Mergus) and the goldeneyes (Bucephala). It is the only member of the genus Mergellus; sometimes included in Mergus, this genus is distinct (though closely related) and might actually be a bit closer to the goldeneyes. The Smew has interbred with the Common Goldeneye (B. clangula).
An unnamed fossil seaduck, known from a humerus found in the Middle Miocene Sajóvölgyi Formation (Late Badenian, 13-12 million years ago) of Mátraszõlõs, Hungary, was assigned to Mergus. However, the authors included the Smew therein, and consequently, the bone is more properly assigned to Mergellus - especially as it was more similar to a Smew's than to the Bucephala remains also found at the site. It is sometimes argued that the Mátraszõlõs fossil is too old to represent any of the modern seaduck genera, but apparently these were all well-distinct even back then.
Fossils from the earliest Pleistocene found in England indicate that the living species was extant 1.5 to 2.0 million years ago.
The drake Smew, with its 'cracked ice' appearance, is unmistakable, and looks very black-and-white in flight. The females and immature males are grey birds with chestnut foreheads and crowns, and can be confused at a distance with the Ruddy Duck; they are often known as "redhead" Smew. It has oval white wing-patches in flight. The Smew's bill has a hooked tip and serrated edges, which help it catch fish when it dives for them.