Goldeneye
The Common goldeneye (Bucephala clangula) is a medium-sized sea duck named for its golden-yellow eye. Its closest relative is the similar Barrow's goldeneye. The genus name of the Common goldeneye comes from the Ancient Greek boukephalos and can be translated as "bullheaded", a reference to the bulbous head shape of the bufflehead.
Adult males of this species 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 brown head and a mostly grey body. Their legs and feet are orange-yellow.
Common goldeneyes are found across Canada and the northern United States, Scotland, Scandinavia, the Baltic States, and northern Russia. They are migratory and most winter in protected coastal waters or open inland waters at more temperate latitudes. Common goldeneyes breed in taiga and are usually found in the lakes and rivers of boreal forests.
Common goldeneyes are social birds that migrate and forage in small flocks. They spend most of their time on the water and are strong swimmers and divers. They feed during the day diving underwater to search for prey. They often synchronize their dives with others and these dives usually last for up to a minute.
Common goldeneyes are carnivores (molluscivores, insectivores). They feed year-round on crustaceans, aquatic insects, and mollusks. Insects are the predominant prey while nesting and crustaceans are the predominant prey during migration and winter. They may also eat fish eggs and aquatic plants.
Common goldeneyes are monogamous and form pairs. It is unknown if the pair will reunite in the next breeding season. Common goldeneyes are aggressive and territorial ducks and have elaborate courtship displays. They usually breed between December and May. The birds nest in cavities in large trees, where they return year after year, though they will readily use nest boxes as well. The female lays 4-9 eggs and the incubation period ranges from 28 to 32 days. The female does all the incubating and is abandoned by the male about 1 to 2 weeks into incubation. The young hatch precocial. They remain in the nest for about 24-36 hours and are capable of flight at 55-65 days of age. Females abandon their broods before they fledge and the broods commonly start to mix with other females' broods.
Common goldeyes are threatened mainly by the loss of their native habitat. Both the breeding and winter habitat of these birds has been degraded by clearance and pollution. Modern forestry management work is also limiting the suitable area for nesting by removing old and decaying trees where goldeneyes like to nest.
According to IUCN Red List, the total population size of the Common goldeneye is around 2,700,000-4,700,000 individuals. The Russian national population consists of around 100,000-1 million breeding pairs and around 10,000 wintering individuals. The European population consists of 489,000-623,000 pairs, which equates to 977,000-1,250,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
