They Of the Golden Eye

By Debbie Wiggins, Golden Eagle Guest Blogger

Common Goldeneye (Bucephala clangula) and  Barrow’s Goldeneye (Bucephala islandica) are medium-size diving ducks. Some traits are shared between the species, but some behavior, how they look and their range set them apart from each other. To state the obvious, all adults have a brilliant golden eye that can be readily seen, even at some distance.  In flight, their wings make a distinct whistling sound.

Common Goldeneye

The breeding male Common Goldeneye has a triangular-shaped head and upper neck that is iridescent greenish-black in color. There is an oval white cheek patch between his bill and eye. The black triangular-shaped bill and sloped forehead contribute to the shape of the head. The sides, breast, belly, and secondary flight feathers are bright white; the back, wings and tail are black.  The folded wing reveals ‘windows’ formed by the black wing and white secondaries.

The female Common Goldeneye has a rich brown head, triangular in shape, sloped forehead and black bill tipped with yellow. She has a brownish-gray back, wings, and tail with white flanks, breast, and belly.

Male Common Goldeneye by Ken Miracle

Barrow’s Goldeneye

The male Barrow’s Goldeneye in breeding plumage has an oval-shaped head that is iridescent purplish-black in color, including the upper neck. There is a large white crescent between the bill and eye. He has a steep forehead and stubby black bill. White sides, breast, and belly contrast with black back, wings, and tail. The folded wing reveals a down-tipped black spur at the shoulder; behind that, a series of small square white spots are seen against the black wing.

The female Barrow’s Goldeneye also has the rich brown head, but it’s oval with a flat top, steep forehead and mostly yellow bill. She has a slate-gray back, wings, and tail with white flanks, breast, and belly.

Male Barrow’s Goldeneye by Ken Miracle

Deep Divers

When diving, goldeneye do so with wings closed and tails spread.  Underwater time can last up to a minute.  These ducks dive clear to the bottom to hunt for food, as much as 30 feet, even turning over small rocks and stones in their search for prey items.  At times, however, goldeneye forage in much shallower depths close to shore. Foraging preferences, like food preferences, change by location and season.  Barrow’s Goldeneye appear to do more shallow foraging than deep diving; the opposite appears true for Common Goldeneye.

Common Goldeneye by Louisa Evers

Winter Fun in Idaho

At this time of year In southwest Idaho, Common Goldeneye is by far the more numerous of the two goldeneye species. They are seen in small flocks, sometimes in large concentrations and often on the Boise River. The majority of Barrow’s Goldeneye overwinter in coastal saltwater habitats. Barrow’s Goldeneye may join Common Goldeneye in Idaho, but in much smaller numbers. Both species will be leaving the Treasure Valley soon to migrate north for breeding season. They’ve been seen recently in the Boise River at the Intermountain Bird Observatory Diane Moore Nature Center.

Both Common Goldeneye and Barrow’s Goldeneye consume some aquatic vegetation, but they prefer mollusks, crustaceans, and aquatic insects such as beetles, water boatmen, caddisfly larvae, and nymphs of dragonfly, damselfly, and mayfly. At times they dine on small fish.  But here’s something really interesting:  large fish compete directly with goldeneye for these same yummy prey.  So, goldeneye often seek to inhabit lakes and ponds with few or no fish.  These lakes and ponds, coincidentally, are often on the acidic side of neutral on the pH scale. Fish don’t tolerate acidic water. No fish, no competition.  Ain’t nature grand!

Hurray For Canada

Goldeneye males and females pair up before they fly north from Idaho in the early spring. They are monogamous. Common Goldeneye are cavity nesters and favor Canada’s boreal forests. Barrow’s Goldeneye often nest in cavities, but they also nest north of the treeline. Year after year females return to nest in the general vicinity of their previous, or natal nest. The male accompanies the female through the process of nest selection, hangs around until the eggs are laid, then returns to his bachelor life.  

Courting Common Goldeneye by Ken Miracle

6-12 eggs are laid and incubation lasts about 30 days. The female coaxes the hatchlings from the nest and to the water, but she does not feed them; they are able to do that for themselves from the get-go. Her skills are utilized in protecting her brood from other waterfowl and in teaching the ducklings to become goldeneye. Females have been observed defending their nests and broods with broken-wing displays similar to that of killdeer. The motherly defense doesn’t last long for Common Goldeneye as they often abandon their brood before they can fly. Ducklings must then fend for themselves or join the broods of other females.

Look closely. Photo by Ken Miracle

Resources

Cornell Lab of Ornithology  allaboutbirds.org & birdsoftheworld.org

Birdzilla.com   Common Goldeneye

Animal Diversity Web  animaldiversity.org   Common & Barrow’s Goldeneye

audubon.org  Online Field Guide

Beauchamp, Guy.  Diving Behavior in Surf Scoters and Barrow’s Goldeneyes

Auk 109(4), 1992 

Poysa, Hannu & Virtanen, Juha.  Habitat Selection and Survival of Common Goldeneye (Bucephala clangula) Broods—preliminary results. Hydrobiologica, 1994.