The Common Goldeneye is a cold-hardy, medium-sized diving duck that breeds worldwide in northern boreal forests. In flight its wings make a distinctive whistling sound, giving rise to its colloquial name, “whistler.” This species readily nests in boxes, facilitating studies of its reproductive biology and management. It is an aggressive and territorial duck and often dominates interactions with competitor species for food and nest sites. Its spectacular courtship displays probably evolved from aggressive postures; they have been intensively studied.
In North America this species typically breeds across forested regions of Canada and winters along the Pacific and Atlantic coasts. During the breeding season, it is primarily insectivorous and prefers lakes (often fishless) with abundant aquatic invertebrates. Fish, crustaceans, and mollusks become a more important part of the diet in winter. Females breed in their second year and make one annual nesting attempt. They usually return year after year to the same nest site; they also commonly lay their eggs in the nests of conspecifics or other cavity-nesting ducks.
Despite threats from acid precipitation, organochlorine contaminants, and deforestation, Common Goldeneye populations remain relatively stable. Nevertheless, this species' nesting habitat requirements and sensitivity to prey quality and availability make it a potentially suitable species with which to monitor the effects of environmental perturbation on boreal wildlife.