The Common Goldeneye (Bucephala clangula) is a medium sized sea duck of the genus Bucephala, the goldeneyes. See also Barrow's Goldeneye.
Adults have yellow eyes. Adult males have a dark head with a greenish gloss and a circular white patch below the eye, a dark back and a white neck and belly. Adult females have a brown head and a mostly grey body.
Their breeding habitat is forested lakes and rivers across Canada and the northern United States, Scandinavia and northern Russia. They nest in cavities in large trees. They will readily use nestboxes, and this has enabled a healthy breeding population to establish in Scotland.
They are migratory and most winter in protected coastal waters or open inland waters at more temperate latitudes.
These diving birds forage underwater. They eat crustaceans, aquatic insects and small fish.
The name fits; this is the most common goldeneye.