Habitat

Primarily wetlands, lakes, and rivers bordered by forests mature enough to provide suitable tree cavities, although rock cavities are used in northern portions of breeding range (e.g., Newfoundland) (Palmer 1976b, Bellrose 1980). Types of forest stands bordering aquatic habitats do not appear to be a factor in breeding-site choice; both coniferous and deciduous trees are used readily for nesting. Over much of central and n. Ontario and e. Quebec, oligotrophic lakes with surface areas between 1.5 and 20 ha are used extensively (DesGranges and Darveau 1985, McNicol et al. 1987a), although in some areas (e.g., Minnesota; Zicus and Hennes 1995) much larger lakes also form primary habitat. In most areas, Common Goldeneyes prefer lakes with clear water and good visibility and with relatively low or simple shoreline configurations lacking significant emergent or submerged vegetation (Nummi and Pöysä 1993, Wayland and McNicol 1994), although stands of bulrush (Scirpus) may be used as foraging areas (e.g., Zicus and Hennes 1995). During brood-rearing, lake clusters or lakes with high shoreline-to-surface-area ratios may be preferred (Eriksson 1983, Wayland and McNicol 1994).

Availability of abundant invertebrate prey appears to influence choice of habitat (Eriksson 1978, 1979, 1983, Eadie and Keast 1982, Wayland and McNicol 1994). Some fish species (e.g., yellow perch [Perca flavescens]) compete with Common Goldeneyes for invertebrate prey (Eriksson 1979, Eadie and Keast 1982); lakes where these fish are present have fewer invertebrates (e.g., McNicol and Wayland 1992) and are thus less suitable for Common Goldeneyes. Surveys demonstrate that Common Goldeneyes often avoid habitats where competitor fish are present (Eadie and Keast 1982, Blancher et al. 1992, McNicol and Wayland 1992). In areas affected by acid precipitation, Common Goldeneyes are abundant on acidic, fishless lakes through all stages of the breeding cycle (McNicol et al. 1987a, Mallory et al. 1993, 1994). Over the extent of its breeding range, this duck does nest successfully on lakes containing fish (e.g., Zicus and Hennes 1995), but evidence suggests that it prefers, when available, habitats with few or no fish. See also Food Habits: feeding, and Breeding: nest site.

Migratory habitats may be used only briefly and appear to focus on feeding areas on large lakes and rivers (e.g., Great Lakes-St. Lawrence system) along which interior birds migrate to coastal regions.

Primarily marine: shallow coastal bays, estuaries, and harbors of Atlantic and Pacific coasts, wherever adequate food is found (Bellrose 1980, Vermeer 1982). Because winter diet is largely mollusks and crustaceans, prefers foraging over sandy, gravel, rocky, or boulder substrates in relatively shallow waters where such prey are concentrated (Vermeer 1982, Duncan and Marquiss 1993). In the interior, also found on larger lake and rivers as far north as open water is available (Bellrose 1980, Afton and Sayler 1982, Foley and Batcheller 1988). Increasingly found in discharge areas near industrial or power-generating stations where waters remain ice-free; capable of foraging in strong current areas, but appears to prefer wider, deeper, and slower-flowing sections of rivers (Afton and Sayler 1982, Duncan and Marquiss 1993). See also Food Habits: feeding.