Behavior

Walking, Hopping, Climbing, Etc

Spends little time on land; females walk only when leading their broods from nest to water, or when moving broods overland to different lakes or ponds (Eriksson 1978). These distances can be as much as 1–2 km. Females rarely perch on tree limbs, unlike many other cavity-nesting ducks, but often sit at entrance to nest cavity, or rest on or near cavity openings when prospecting for nest sites (Eadie and Gauthier 1985).

Flight

Flies in small, compact groups (6–12 individuals; Bellrose 1980).  Flight is fast (72 km/h in Scandinavia) and wingbeats rapid (9 wingbeats/s; Palmer 1976b), producing a characteristic “whistling” sound, particularly on cold days. Becomes airborne easily for a diving duck, running or “pattering” only briefly (1–2 m) on surface before taking wing. Flies low on short flights, but like most sea ducks, flies high on long travels or overland. When approaching nest site, female may fly straight into nest hole with little reduction in speed, or may circle in front of nest, gliding the final distance with wings set. She enters by turning into a slight stall, hitting the bottom edge of the opening with legs extended, and pivoting into the opening. Females have been observed to miss the entrance on approach (M. C. Zicus pers. comm., MLM).

Swimming And Diving

A strong swimmer and diver, spending most of its life on water. Dives actively and frequently, usually in small groups, often synchronously. Swims low in water when feeding with head stretched forward (Phillips 1925). Dives easily without an exaggerated leap or plunge. Plumage becomes compressed before diving. Holds wings close to body underwater, using only feet for propulsion; some reports of Common Goldeneyes using wings “half-spread” when feeding (Bent 1925).

Preening, Head-Scratching, Stretching, Bathing, Etc

Preens primarily on water, also on floating logs, docks, or timber at water’s edge. Several preening and maintenance behaviors have become ritualized and incorporated into copulatory and courtship displays (e.g., Drinking, Head-lifting, Bathing, Display-drinking, and Wing-and-leg Stretch; see Sexual Behavior, below).

Sleeping And Roosting

Often described as “restless.” Spends much time moving or diving. In fall and winter, small flocks gather at dusk in dense rafts, usually offshore. These rafts scatter and break up into smaller groups to feed in early morning. Large numbers may assemble at stopover areas, but prevalent social group appears to be a small number of individuals (Palmer 1976b). Rests with head tucked back on shoulders, usually for short intervals, scanning periodically. Adults tend to be wary (Bent 1925).

Daily Time Budget

Before incubation and during incubation recesses, females spend most of daylight hours feeding (Fig. 2). During brood-rearing, this pattern shifts and females spend more time alert and less time feeding (Fig. 2). Time budgets of females with broods differed among study lakes in Minnesota (Zicus and Hennes 1994) and among study sites in British Columbia, Ontario, and Minnesota (JME, MLM, and M. C. Zicus unpubl. data). Habitat quality and presence of competitors significantly influence activity patterns (MLM), as does sex (Zicus and Hennes 1994; also see Fig. 2). Males spend most of their time feeding or in maintenance activities (sleeping, loafing, preening, swimming; Fig. 2). Relative to females, males spend less time feeding and more time in agonistic (territorial) behaviors during egg-laying and incubation (Fig. 2).

Duckling activities are dictated by growth requirements; feeding dominates daily time budgets (69.6% of time), followed by maintenance (17.8%), vigilance (4.8%), and other behaviors (5.2%) (n = 59 observation periods, 813 min; JME). Class-III ducklings spend less time than Class-II ducklings feeding (63.6% vs. 77.6%, respectively) and more time in maintenance (22.8% vs. 10.7%) and vigilance (6.5% vs. 1.4%) (JME).

Physical Interactions

Brief fights occur among males. Males submerge toward an intruder and surface near or under the rival. Short chases ensue, with individuals occasionally diving to escape pursuit. Fights end when the intruder(s) leave the territory, often pursued in the air by the territorial male. Females defending brood territories are more aggressive, particularly in areas with dense breeding populations. Females frequently dive and attack intruders, including ducklings of other broods. Several instances of infanticide have been observed in British Columbia, involving both conspecific broods and broods of other species (JME).

Communicative Interactions

Common Goldeneye drakes defend females and territories during breeding season using several displays. The most common, the Threat Display, consists of a male swimming low in water, head stretched forward with bill parallel to or touching water (Palmer 1976b, JME). Males swim in Threat Display toward an intruder, occasionally raising and turning head. If intruder persists, territorial male dives and swims submerged toward intruder. When the rival is another male, the two often submerge together, although both frequently emerge at a greater distance apart.

Females use similar display when defending brood territories, but will dive and physically approach intruders more directly.

Territoriality

Early reports suggested that Common Goldeneye males were not territorial (Cartar 1958) or defended only a moving territory around the female (Gibbs 1961). Savard (1984), however, demonstrated that Common Goldeneyes defend fixed breeding territories, a conclusion corroborated by studies in the Cariboo Parklands of British Columbia (JME). Degree of territoriality in this species may depend on breeding density. Paired males establish territories soon after arrival on breeding grounds and maintain these territories until females begin incubation. Drakes defend territories using ritualized displays (above) and chases (Savard 1984, JME). Territories are also defended against congeneric Buffleheads and Barrow’s Goldeneyes in areas of sympatry (Savard 1984, JME). Territory owners are dominant within their territory, but both goldeneye species dominate and exclude the smaller Bufflehead. Common Goldeneye males appear to be less aggressive than Barrow’s Goldeneye males. Females rarely play a role in defending pair territories, spending most of their time feeding or resting. The primary role of pair territories may be to provide undisturbed feeding time for the hen, and perhaps to ensure paternity of the male.

Densities of territorial pairs in British Columbia averaged 0.70 pairs/km of shoreline (SE 0.07, range 0–2.58, 90 lake-years) or 0.09 pairs/ha (0.01, 0–0.31 pairs; JME). Densities of territorial pairs in Minnesota (1980–1985) averaged 0.5–3.5 pairs/km of shoreline, or 0.02–0.3 pairs/ha (M. C. Zicus unpubl. data). Variation in lake area or degree of shoreline complexity may preclude meaningful comparisons of densities among studies.

In a breeding population in central British Columbia, females defend brood territories in a manner similar to that described for Barrow’s Goldeneye females (Savard 1982) and Buffleheads (Gauthier 1987a). Brood territories are often, but not always, adjacent to the nest site. Early-nesting females establish territories nearest their nest site; late-nesting females may be excluded to more distant areas or different water bodies. All activities of the brood are restricted to the territory; the hen defends the area aggressively from conspecifics as well as other species. Density of brood territories in British Columbia averaged 0.17 broods/km of shoreline (SE 0.04, range 0–1.88, 72 lake-years), or 0.02 broods/ha (0.01, 0–0.31 broods; JME). In Minnesota, brood densities averaged 0–1.9 broods/km of shoreline, or 0–0.2 broods/ha (M. C. Zicus unpubl. data). In Ontario and Minnesota, brood territories do not appear to be fixed; broods move frequently along the shoreline (M. C. Zicus pers. comm., JME). Differences in the degree of brood mobility may relate to lake size or morphology, food resources, brood densities, or human (recreational) use of lakes.

Territoriality has not been reported outside the breeding season for Common Goldeneye, although congeneric Barrow’s Goldeneye defends winter territories on the coast of British Columbia (Savard 1988).

Mating System And Sex Ratio

Only monogamy reported. Savard (1984) reports 1 occurrence of a male defending 2 females in Columbia Valley, British Columbia.

Little known about sex ratio. Data from spring counts presented in Bellrose (1980) suggest that 60.4–61.5% of Common Goldeneyes are males; Sayler and Afton (1981) found that adult males comprised 50.7–66.0% of Common Goldeneyes wintering on Mississippi River. Data on Common Goldeneyes shot by hunters (1976–1991) in e. Canada and ne. U.S. suggest that males comprise approximately 50% of hatch-year birds shot in e. North America each year, whereas males comprise approximately 65% of adults shot each year (preliminary analysis, H. Boyd pers. comm.).

Pair Bond

Courtship Displays (see Fig. 3). Courtship occurs in small groups; Afton and Sayler (1982) observed an average of 4.4 males and 1.2 females per display group. Data on courtship displays have been intensively studied; summary below follows detailed descriptions from Dane and van der Kloot (1964), Palmer (1976b), and Johnsgard (1978).

Males have a spectacular and complex courtship behavior exhibited from Dec through Apr that leads to pair formation and maintenance of pair bond. Displays of drake (and associated durations) include Head-throw (1.4 s), Slow Head-throw-kick (2.2 s), Fast Head-throw-kick (1.25 s), Bowsprit (1.95 s), Head-throw-bowsprit (2.0 s), Nodding (0.7 s/nod), Masthead (4.8 s), Ticking (0.19 s), Head-flick (0.2 s), Head-forward (2.45 s), Head-up (2.6 s), Head-up-pumping (0.55 s), Head-back (1.15 s), and Head-back-bowsprit (1.55 s). Most distinctive of these displays are the Head-throw-kicks, where male thrusts his head straight forward, then lowers it to his rump with his bill pointed back past vertical, at which point he utters a single, grating call, thrusting his head rapidly forward (sometimes flicking it from one side to the other) while kicking water out with his feet. Nodding occurs when male stretches and withdraws his head forward at about 45¿, tracing an elliptical path with his bill. Masthead is a jerky, mechanical display in which male lowers and stretches his head parallel to water for up to 3 s, then quickly jerks his head upright pointing bill vertically, then snaps his head back down to water level and holds it there while paddling. Display flight consists of drake raising his head in an alarm posture, flying a short distance away from the group, then stalling and landing on water; sometimes several males will follow a female.

Female courtship involves Head-up (up to 72 s), Head-forward (0.85 s), Dip (1.7 s), and Head-flick (0.25 s) displays. Head-forward, a lowering and swinging of neck and head forward, is the most common female display, performed while birds are in groups in response to a leading male performing Head-throws and Ticking. Female is silent.

Copulation and Copulatory Displays. Copulation occurs on water. Female usually initiates copulatory sequence by assuming a prone position on water, holding it for up to 15 min. Occasionally, female may perform ritualized Drinking, Head-lifting, or Bathing. Male usually begins with a Bill-shake (0.9¿s), followed by Display-drinking (2.0 s) and the distinctive Wing-and-leg Stretch (5.4 s), whereby male turns on one side and stretches out wing and leg. A series of Head-flicks (0.25 s) and Head-rubbing (0.75 s) may occur, followed by a Crescendo (7.25 s) of rapid Bill-shakes and Display-drinking (0.5 s).

Copulation averages 8.3 s. Male overlies female, then holds nape of her neck, at which point she is nearly submerged. Tail-wags and wing-lifting may occur, and male may remain mounted for 45 s. Rotations (4.8 s) occur as male slips off but continues to hold female’s neck while beginning to swim. Postcopulatory Steaming (13.6 s) then occurs; male holds his head stiffly vertical, crest expanded, and swims away, after which both male and female perform exaggerated Postcopulatory Bathing.

Duration And Maintenance Of Pair Bond

Pair bonds generally begin to form in Dec and last until male abandons female in early incubation; duration of pair bond in Common Goldeneye is unknown, but at least 5 other species of sea ducks (Tribe Mergini), including closely-related Barrow’s Goldeneye, are known to have pairs that reunite for > 1 breeding season (Gauthier 1987b).

Extra-Pair Copulations

Forced copulations occur in many waterfowl but have not been reported for Bucephala . Males defend females during egg-laying, suggesting that extra-pair copulations are a potential threat. DNA fingerprinting analyses of Common Goldeneye broods in British Columbia reveal no evidence of extra-pair paternity (JME).

Degree Of Sociality

Usually observed as pairs or small groups (4–40 birds) in winter (except when large winter roosting concentrations are formed); in summer, females are generally observed individually, whereas males molt in scattered small groups but may form large flocks of several hundred birds (Palmer 1976b). Migration of inland-nesting birds tends to occur in small flocks.

Play

No information.

Nonpredatory Interspecific Interactions

Usually avoids other species; may mix with Barrow’s Goldeneye in rafts (Palmer 1976b). See also Spacing, above; and Breeding: nest site, and brood parasitism, below.

Kinds Of Predators And Manner Of Predation

Incubating females and broods are most vulnerable to predation. Main predators of incubating females: black bear (Ursus americanus), pine marten (Martes americanus), and mink (Mustela vison); also raccoons (Procyon lotor) in southwest part of breeding range. On clutches: above species, as well as Northern Flicker (Colaptes auratus) and red squirrel (Tamiasciurus husonicus). On females and their broods: various hawks and owls, Bald Eagle (Haliaeetus leucocephalus), Golden Eagle (Aquila chrysaetos), and fish such as northern pike (Esox lucius) (Palmer 1976b, MLM, JME, HGL, M. C. Zicus pers. comm.).

Response To Predators

Females defend nests by performing Broken-wing Distraction Displays in late incubation and when accompanying their brood (Mallory and Weatherhead 1993b; see also Breeding: incubation).