The common scoter is a large billed, slim necked, social, sea duck. During the non-breeding season the adult male has an all black body with a purplish hue to the upper parts and dark grey tips to the primary and secondary flight feathers. The tail is long and often seen raised whilst the bird is in the water. The head is rounded and the large pointed bill is predominantly matt black with a yellow patch on the ridge of the upper mandible, commencing behind the nostrils and extending forwards towards, but not meeting, the tip. Legs and feet are a matt black or dark grey and the eyes are a very dark brown. During the summer breeding season the upperwing areas are more brownish in colour. Adult females are a similar basic shape to the male although smaller and with a less pronounced base to the bill. They have a predominantly sooty brown coloured body with a black crown and cap extending across the forehead and to just below the eyes, ending at the nape of the neck. The cheeks, lower facial area and neck are greyish white morphing into the dark brown body mid way down the neck. The bill is slate grey and lacks the male’s yellow nasal patch. The eyes are a lighter brown than the male and both feet and legs are a dark matt grey. The plumage of juveniles is similar to the female although generally paler, particularly across the underparts.