The Common Goldeneye (Bucephala clangula) is a medium-sized bird from the merganser family. From the tip of the bill to the end of the tail it measures 40 to 48 cm, and its wingspan is 62 to 77 cm. It is quite a chunky bird with a large head on a relatively short neck. We will recognize the male by its white chest, belly and flanks, and by its black tail and back, from which some black streaks extend onto the flanks. Its most characteristic feature is a dark green head with a metallic sheen, which is adorned by a bright yellow eye, and in front of the tall dark gray bill there is also a white oval patch. Females and juvenile individuals are cryptically colored. Their body is gray-brown with a white patch in front of the tail, and the head is dark brown. Females have a yellow eye, while the eyes of the young are brown.
The Common Goldeneye is a shy, diurnal bird that mainly feeds on aquatic invertebrates, for example insect larvae, crustaceans and molluscs, and on occasion it also catches a small fish. Particularly in autumn it likes to diversify its diet with seeds and also with shoots and underground parts of plants.
The Common Goldeneye migrates mainly from its breeding area to wintering areas. It nests on clean water bodies in forested landscapes, as it is one of the species that breed in tree hollows, which are usually hollowed out by magpies. It prefers lakes or slow-flowing waters with few nutrients, in which there are no fish and therefore correspondingly more invertebrates. In winter, goldeneyes gather in larger flocks, which often winter along the coast or at river mouths. They can also regularly be observed on unfrozen inland waters. In Slovenia, goldeneyes winter here or simply stop here during spring or autumn migration.
The greatest threat to the goldeneye is the degradation of its habitat. Drying up and regulation of waterways, and especially acid rain, have a devastating impact on its habitat. The areas where it winters are mainly threatened by pollution.
