The Common Scoter is a sea duck whose males and females differ in color. It breeds in northern European wetlands and moves to coastal waters for winter.
Breeding males are black overall, while females are brown with a paler face. These plumage descriptions are separated by sex and season.
Common scoters sometimes dive almost simultaneously in small flocks and return to the surface together. Observations in North Wales, Britain, recorded both individual dives and flock dives in which birds resurfaced together or within a few seconds of one another. Along their wintering coast, they alternate between diving for food and time at the surface.
A 2006 paper compared dives observed from shore and at sea during 2003–2004. Mean dive durations at two sites were about 35 and 37 seconds. Water depths beneath the birds, calculated using tidal models, averaged about 7 and 11 metres. Flocks also took flight as a research vessel approached; large flocks were observed leaving while the vessel was still 1–2 kilometres away. The sea where these ducks dive for food is also used by vessels carrying people.
An extinction-risk assessment has not been added yet.
Liverpool Bay in Britain is a Special Protection Area designated for common scoters and other birds outside the breeding season. The government nature conservation advisory account sets objectives to maintain or restore the extent and distribution of habitats, their ecological functions, bird populations and their distribution within the bay. Disturbance, including shipping, and pressures associated with fishing and other activities are identified as issues to consider in protecting the site.