The smew is a species of duck and is the only member of the genus Mergellus.

The drake smew, with its ‘cracked ice’ and ‘panda’ appearance, is unmistakable and looks very black-and-white in flight. The females and young 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 beak has a hooked tip and serrated edges, which help it catch fish when it dives. The male is the clearest duck to be found in Finland and can be confused with a seagull while swimming. Especially white plumage has black marks between the beak and eyes in the back of the neck and middle back. Generally, the female looks like the golden-eye, but is more slender and shows white on its neck, which extends over its cheeks to form a clear boundary with its reddish brown cap. Its wings have the same drawings than males. 

It nests in a hole or a nest box. It lays between 7 and 11 eggs in May, incubated by the female for 26 to 28 days. The chicks leave the nest soon after hatching and quickly learn to find food alone but they are clustered near their mother. They take off after about 10 weeks.