Common goldeneyes are medium-sized diving ducks. Males are slightly larger than females, from 45 to 51 cm in length (40 to 50 cm in females) and about 1000 grams (800 grams in females) weight. Males also have more brightly colored plumage for most of the year. Breeding males have a brilliant, greenish-black head with an oval, white patch at the base of the bill. Their sides, breast, belly, and secondary feathers are bright white and their back, wings, and tail are black. Female feathers are more muted, with rich brown heads, greyish backs, wings, and tails, and white sides, breasts, and bellies. Mature adults of both sexes have bright, deep, yellow irises, giving them the common name "goldeneye." Immature individuals have brownish irises. In flight their wings produce a whistling sound.
Common goldeneyes are found throughout North America and Eurasia. In summer they breed in the northern parts of their range, mainly in Canada, the northern United States, northern Europe, and northern Russia. In winter they are found mainly in large, inland lakes and along the coasts of North America from Alaska to Baja California, Newfoundland to Florida, and the northern Gulf of Mexico. In Eurasia they are found in all coastal waters from Scandinavia to the Mediterranean, Black, and Caspian Seas and from Kamchatka to Japan. They are also found in inland lakes that remain ice-free.
During the summer, common goldeneyes are found on northern lakes and rivers that are surrounded by mature forests where tree cavities can be found for nesting. They prefer lakes with clear water, little vegetation, and plenty of invertebrate prey.
During the winter, non-breeding season, common goldeneyes are found mainly in coastal waters and large, interior lakes and rivers. They prefer areas with shallow water and sandy, gravel, or rocky substrates. They seem to prefer slow-flowing water.
Common goldeneyes are monogamous. Pairs form in December and last until the male abandons the female at the beginning of incubation. Males use a complex set of courtship displays from December to March to establish and maintain the pair bond. The most spectacular display is the "head-throw-kick," in which a male repeatedly thrusts his head forward, then moves it back towards his rump and utters a call. He then flicks his head forward again while kicking the water with his feet.
Reproduction in common goldeneyes has been well-studied because they are relatively common in northern boreal areas and they will nest in boxes, making them easy to observe. Females lay from 4 to 12.3 greenish eggs in a single clutch each season. Females lay 1 egg every other day. Common goldeneyes nest in tree cavities, but will accept nest boxes also. Females find nest cavities and line them with other materials and downy feathers. Nests are generally within 1.3 km of water. Females tend to nest in the same place each year and near to the spot where they were hatched. Females incubate the eggs for 28 to 32 days. They leave the nest occasionally during the day to forage. Eggs all hatch within 12 hours of each other. Females first to breed at over 2 years old.
Young leave the nest and can walk and swim within 24 to 36 hours after hatching. The mother sits at the nest cavity entrance until all of the young jump to the ground. Females lead their brood away from the nest site to a brooding territory up to 10 km away. Females defend the young and brood them at night and during cold weather. Females abandon their broods before they can fly, usually around 5 to 6 weeks old.
Males can live to 11 years and females to 12 years, one common goldeneye lived to 15 years. Hunting, predation, and diseases are the leading causes of death in adults. Many hatchlings die within their first few weeks of life from predators and from being exposed to cold, wet weather.
Common goldeneyes spend most of their time on the water. They only walk when moving broods from the nest to the water. They can fly up to 72 km per hour with 9 wingbeats per second. Common goldeneyes are excellent swimmers and divers, they forage in small groups. Common goldeneye populations migrate between their summer, breeding ranges and wintering grounds.
Common goldeneyes forage in small groups and are social except for the breeding season. Males and females defend small territories that include the nest during breeding season.
Common goldeneyes are mainly silent outside of the courtship and nest-finding period. Males make short, faint "peent" calls during courtship displays. Females make "gack" sounds when looking for nest sites or when disturbed.
Common goldeneyes eat mainly aquatic insects during breeding season in northern, boreal lakes. In their winter ranges they rely on fish, crustaceans, and mollusks. They may also take some seeds and tubers. Important insect prey include caddisfly larvae, water boatmen, dragonfly and damselfly nymphs, mayfly nymphs, and beetles. Common goldeneyes usually hunt in open water less than 4 meters deep. They dive to catch prey and dives can be from 10 to 55 seconds long. Downy hatchlings feed at the surface for their first few days but then begin short dives. Prey is eaten underwater.
Most predators take females and young in nests. North American predators include black bears, American martens, mink, raccoons, hawks, owls, bald eagles, and golden eagles. Hatchlings are also taken by northern flickers, red squirrels, and northern pike. Females distract predators with broken-wing displays.
Common goldeneyes compete directly with fish for prey and tend to be found on fish-free lakes more often than on lakes with fish.
Like many other species of ducks, common goldeneyes practice nest parasitism towards other common goldeneyes. Females lay eggs in the nests of other females. Clutches with introduced eggs can be as large as 24.
Common goldeneyes are susceptible to botulism (Clostridium botulinum), avian cholera (Pasteurella multocida), and duck viral enteritis. Parasites include several species of protozoans, flukes, and nematodes.
There are no known adverse effects of common goldeneyes on humans.
Common goldeneyes are hunted throughout much of their range. (Eadie, et al., 1995)
Common goldeneye populations are relatively stable despite threats to their aquatic habitats, such as acid rain, contamination, and habitat destruction. They are considered "least concern" because of their large range, large population size, and no documented population declines. They are protected as a migratory bird under the U.S. Migratory Bird Act.
Common goldeneyes are sometimes called "whistlers" because of the whistling noise their wings make in flight. (Eadie, et al., 1995)
Tanya Dewey (author), Animal Diversity Web.
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