What is the difference between a Common Goldeneye hen and a Barrows goldeneye hen?

The Common Goldeneye (Bucephala clangula) and Barrow’s Goldeneye (Bucephala islandica) are two closely related species of diving ducks found in the Northern Hemisphere. While the males of each species are easy to distinguish, with their striking green heads and white circular facial patches, the females are much more similar in appearance. This can make differentiating between a Common Goldeneye hen and a Barrows Goldeneye hen challenging for many birders.

In this article, we will explore the key physical differences between these two goldeneye species and provide tips for identification. We will also look at their breeding, habitat, and migration patterns to understand where overlap between the species may occur. An awareness of the subtle features that set these ducks apart will help bird enthusiasts correctly identify Common vs. Barrows goldeneye hens in the field.

Key Identification Features

When seeing a female goldeneye duck, there are a few key features to pay attention to in order to determine whether it is a Common or Barrows:

Bill Color

The bill color is one of the most reliable ways to tell Common and Barrows goldeneye hens apart.

– Common Goldeneye hen: The bill is dull yellow to olive green in color. It may have a small black marking at the tip, but most of the bill is yellowish.

– Barrow’s Goldeneye hen: The bill is blue-gray, with a large black tip that covers nearly one third of the bill. Very little yellow is visible.

Head Shape

Subtle differences in head shape can also aid identification:

– Common Goldeneye hen: Slightly more rounded head shape. Forehead has a steeper slope.

– Barrow’s Goldeneye hen: Head is flatter on top with a more gradual sloping forehead. Crown can appear somewhat flat.

Contrast in Head Coloring

The contrast between the dark cap on the head and the sides of the face differs between the species:

– Common Goldeneye hen: Less contrast between the brown cap and whitish cheeks/throat. Transition is more subtle.

– Barrow’s Goldeneye hen: Sharper contrast between blackish cap and white sides of head. Demarcation is more distinct.

Similarities Between Species

While the bill color, head shape, and contrast in head patterning are useful clues for identification, Common and Barrows goldeneye females do share many physical similarities that can make them tough to differentiate in the field:

– Both have a dark brown head with a pale yellowish-tan patch below the eye.

– Their bodies are similarly colored grey-brown on the back and upper-wings, with a paler grey breast and white belly.

– In flight, they share pointed, straight edged wings and rapid wingbeats.

– Their body size and structure are very comparable.

So when seen at a distance or in poor light, an out-of-range female goldeneye may be challenging to positively identify to species using physical features alone. Often the best clue will be location and range.

Range and Habitat

Understanding the range and habitat preferences of Common vs. Barrow’s goldeneyes can provide helpful context for identification:

Common Goldeneye

• Breeds across northern Eurasia and the boreal forest regions of Canada and Alaska.
• Winters farther south throughout temperate regions near lakes, ponds, rivers and coastlines.
• Common in the British Isles and throughout most of Europe.
• Rare vagrant to Iceland and southern Asia.

Barrow’s Goldeneye

• Breeds exclusively in northwestern North America, from Alaska to central British Columbia.
• Winters in western North America along the Pacific Coast south to California.
• Very rare in eastern North America and Europe.
• Occasional vagrant to Japan and the Hawaiian Islands.

So a female goldeneye observed during breeding season in Scotland, for example, is much more likely to be a Common Goldeneye, while one seen in winter along the British Columbia coast is more likely to be a Barrow’s. Paying attention to location and seasonality reduces misidentifications.

Behavioral Differences

Beyond physical features, some behavioral differences may help distinguish Common and Barrow’s goldeneye hens:

Nest Sites

– Common Goldeneye: Often nests in tree cavities near lakes or rivers. Readily uses nest boxes.

– Barrow’s Goldeneye: Prefers to nest in cliffside crevices and rock cavities near mountain rivers and streams. Does not typically use artificial nest sites.

Habitat Use

– Common Goldeneye: Inhabits a wide variety of freshwater habitats including lakes, marshes, ponds and slow rivers.

– Barrow’s Goldeneye: Favors rapid mountain rivers and turbulent streams in higher elevation areas.

Wing Flap in Flight

– Common Goldeneye: Slow, lazy-looking wingbeats with wings held slightly arched when flapping.

– Barrow’s Goldeneye: Stiffer, faster wing flapping with wings held straight and level.

Hybridization Between Species

In some parts of their overlapping range such as Alberta and Alaska, Common and Barrow’s goldeneyes are known to occasionally interbreed. The resulting hybrid hens can show intermediate traits that make differentiating between the parent species difficult. Features like bill coloration and flank contrast may be ambiguous.

If seen in an area of known hybridization, other identification cues like behavior, voice, associates, and DNA analysis may be needed to properly identify a goldeneye hen to species or hybrid status. Records of suspected hybrids should be carefully documented.

Summary Comparison

Conclusion

Telling apart a female Common Goldeneye from a Barrow’s Goldeneye can be tricky, even for experienced birders. However, by carefully noting bill color, head shape, facial patterning, range, habitat, and behavior, accurate identification is possible with practice. Learning how to distinguish these similar northern ducks will help avoid misidentifications and expand one’s birding skills. With a bit of dedicated study, puzzling out subtle goldeneye hens in the field can become much easier.