Medium-sized diving duck. Compact, "chunky" appearance with short neck and round body; short, gray-black bill. Breeding males have striking pattern of iridescent greenish-black head with bright, oval (rather than crescent of Barrow's Goldeneye) white patch at hind base of bill. Brilliant white sides, breast, belly, and secondaries contrast with black back, wings, and tail. Females have chocolate brown head; gray back, wings and tail; and white flanks, belly, and breast. Immature and eclipse males are difficult to distinguish from females. Both sexes have bright amber irises (hence the name "golden-eye"); irises are more brownish in young. Wingbeat is rapid with a relatively deep arc; produces distinctive "whistle" (Eadie et al. 1995).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
See Tobish (1987) for details on identification of Barrow's and Common Goldeneyes in all plumages.
Western Hemisphere Range
Migration in the Bozeman area is from March 10 to May 5 and November 10 to December 20, with peaks March 25 and intermittently in November (April and November statewide) (Skaar 1969).
Breeding birds usually are found in forested wetland habitats (Johnsgard 1986). In migration, they occur on both lakes and rivers (Skaar 1969).
During breeding season, the Common Goldeneye 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 (Eadie et al. 1995).
Silloway in 1901 reported this species to be the most abundant duck in the Flathead region--a distinction it no longer holds. However, Weydemeyer reports it to be almost as common as Mallards in the Fortine area.
This species readily nests in boxes. A cavity nester, uses live or dead trees, but infrequently will attempt to nest in other sites such as rock crevices. Females usually return to the same nest site year after year. Eggs are elliptical to oval. Greenish in color (Eadie et al. 1995). The breeding period in Montana is early May to mid-July. Hatching dates in the Fortine area are estimated from early May to early July. The average brood size in the Fortine area was nine.