The barrow’s goldeneye and common goldeneye are two closely related species of diving ducks found in North America. They belong to the genus Bucephala within the family Anatidae. Though they overlap in range and look very similar, there are some key differences between these two goldeneye species in terms of their appearance, habitat, diet, breeding behavior, and conservation status.
Quick Identification
The barrow’s and common goldeneyes can be very tricky to distinguish in the field due to their similarity in size and plumage. However, there are some subtle differences to look for:
- Barrow’s goldeneye males have a round white spot between the eye and bill, while common goldeneye males have an oblong white patch.
- Barrow’s goldeneye males have a slightly darker head that contrasts more with the white sides.
- Female barrow’s goldeneyes have yellow eyes versus brown eyes in female common goldeneyes.
- Barrow’s goldeneyes have a flatter head profile while common goldeneyes have a more angular head shape.
- In flight, barrow’s goldeneyes show whitish underwings versus gray underwings in common goldeneyes.
Range & Habitat
The barrow’s and common goldeneyes have overlapping but distinct breeding and wintering ranges in North America:
Barrow’s Goldeneye
- Breeding range: Western North America from Alaska to British Columbia and south to Oregon and Wyoming.
- Wintering range: Pacific coast from Alaska to Baja California, some interior lakes and rivers, and Hawaii.
Common Goldeneye
- Breeding range: Boreal forests across Canada and Northern U.S. states.
- Wintering range: Throughout most of U.S., along Pacific and Atlantic coasts, Great Lakes region, and rivers/reservoirs in the interior west.
During the breeding season, barrow’s goldeneyes are found mainly in forested lakes and rivers in mountainous areas of the west. Common goldeneyes breed primarily on wooded lakes and ponds across boreal and northern forest regions.
In winter, barrow’s are mostly limited to the Pacific coast and interior western lakes while common goldeneyes have a widespread winter range including both coasts and interior rivers and lakes.
Physical Description
As diving ducks in the genus Bucephala, the barrow’s and common goldeneyes share a similar compact, chunky body profile with a short neck and rounded head. However, there are some physical differences:
Size
- Barrow’s goldeneye: 16-19 inches long with a 26-29 inch wingspan. Weighs 1.6-2.3 lbs.
- Common goldeneye: 18-21 inches long with a 30-34 inch wingspan. Weighs 2.3-3.1 lbs.
The common goldeneye is slightly larger than the barrow’s on average.
Coloration
Males of both species have iridescent greenish-black heads with a round or oval white patch near the bill and another white patch behind the eye. However, the barrow’s male has a head that appears flatter and more triangular from the side view. The head is also darker black contrasting more sharply with the white sides.
The common goldeneye male has a more rounded head profile and slightly lighter colored head that blends more gradually into the white sides.
Bill Shape
The bill shape differs slightly between the two species:
- Barrow’s goldeneye – short stubby bill, rounded tip
- Common goldeneye – longer and more angular bill, pointed tip
Behavioral Differences
While the barrow’s and common goldeneyes share many behavioral traits as diving ducks, there are some subtle differences:
Diving & Feeding
Both species dive for food and are adapted for swimming underwater. However, the common goldeneye tends to dive deeper on average than the barrow’s goldeneye.
Common goldeneyes regularly dive 20 feet or more while barrow’s goldeneyes dive no more than 12 feet typically. This allows common goldeneyes to access different food resources.
Flight
In flight, barrow’s goldeneyes have faster wingbeats compared to common goldeneyes. Their flight profile appears flatter and more direct.
Common goldeneyes are slower and less agile flyers with a more arched, labored flight profile.
Nesting
Barrow’s goldeneyes nest almost exclusively in natural tree cavities, especially old woodpecker holes. They rarely use nest boxes.
Common goldeneyes frequently nest in artificial nest boxes in addition to natural cavities. Providing nest boxes has helped increase breeding populations.
Winter Flocking
During winter, barrow’s goldeneyes form large dense flocks on lakes and coastal bays. Flocks may contain hundreds of individuals.
Common goldeneyes form smaller, looser flocks in winter and are more dispersed across a variety of open water habitats.
Diet & Feeding
The diets of barrow’s and common goldeneyes consist largely of similar animal foods acquired by diving. However, their relative dependence on certain food sources differs:
Barrow’s Goldeneye Diet
- Insects: Up to 80% insects during breeding season such as damselflies, caddisflies, water boatmen.
- Crustaceans: Not a major part of diet but will eat some mollusks and amphipods.
- Fish: Occasionally eat fish eggs and very small fish.
- Plants: Little plant material in their diet.
Common Goldeneye Diet
- Insects: About 50% insects, more in summer/less in winter.
- Crustaceans: Significant amount of mollusks and amphipods.
- Fish: More reliant on fish like minnows and small sculpin.
- Plants: Will eat some aquatic vegetation and seeds.
So while both are primarily carnivorous, the barrow’s depends more heavily on insects while the common eats a higher proportion of crustaceans and fish.
Breeding & Nesting
There are some key differences in the breeding ecology and nesting behaviors of these two closely related goldeneye species:
Breeding Season
- Barrow’s goldeneye: April to July
- Common goldeneye: April to June
The barrow’s has a slightly longer breeding period lasting through early summer.
Pairing
Male barrow’s and common goldeneyes use similar displays to establish pair bonds with females during courtship (head throwing, neck stretching, rapid foot paddling). However, the barrow’s male displays tend to appear more aggressive and energetic.
Nest Sites
As mentioned previously, barrow’s goldeneyes strongly favor natural tree cavities for nesting whereas common goldeneyes readily use artificial nest boxes. Barrow’s are also more likely to reuse nest sites in successive years.
Clutch Size
- Barrow’s goldeneye: Typical clutch of 6-7 eggs (range 5-11)
- Common goldeneye: Typical clutch of 8-11 eggs (range 5-15)
Common goldeneyes have slightly larger clutch sizes on average.
Incubation & Care
Only female goldeneyes incubate eggs and care for the young. Incubation takes about 30 days for both species. Ducklings fledge at around 60-70 days. Males leave before incubation starts.
Population Status
Based on global population estimates and trends, the barrow’s and common goldeneyes have noticeably different conservation statuses:
Barrow’s Goldeneye
- Global population estimate: ~125,000
- Population trend: declining
- Conservation status: Near threatened
Common Goldeneye
- Global population estimate: ~500,000-1,000,000
- Population trend: increasing
- Conservation status: Least concern
The larger and more widespread common goldeneye is considered a species of least concern by conservation groups. However, the smaller barrow’s goldeneye is experiencing ongoing population declines, especially in parts of its western breeding range, earning it a classification as near threatened. Factors like habitat loss, nest competition, and human disturbance are all potential threats to the barrow’s goldeneye’s limited and fragmented breeding habitat.
Summary of Differences
In summary, while the barrow’s and common goldeneyes share very similar appearances and diving duck behaviors, some of the key differences to note include:
- Barrow’s has a flatter, more triangular head profile
- Barrow’s has a stubbier bill and rounder head
- Barrow’s is slightly smaller in size
- Barrow’s shows more whitish underwings in flight
- Barrow’s prefers western forests while common is widespread across the boreal
- Barrow’s depends more on insect prey while common eats more fish
- Barrow’s favors natural cavity nesting sites
- Barrow’s forms larger winter flocks
- Barrow’s has a smaller global population and is near threatened
Being aware of these subtle differences allows birders and conservationists to better distinguish these similar goldeneye species in the field and also understand their distinct habitat needs and population vulnerabilities. While they may look almost identical at first glance, each species fills an important and unique ecological niche across North America’s northern forests and western mountains.
Conclusion
Barrow’s and common goldeneyes represent an excellent example of how closely related bird species can evolve and adapt to occupy different geographical ranges and ecological roles. While their evolutionary paths have diverged, leading to the distinctive traits of each species covered here, they remain united by their shared characteristics as handsome diving ducks of the genus Bucephala. Their similar appearances and behaviors showcase the complex interplay between convergent evolution and divergent specialization seen across waterfowl taxonomy. Carefully noting field marks like head shape, wing color, and bill profile allows even experienced birders to tell these look-alikes apart and appreciate the subtle beauty of each unique species. With populations of the barrow’s goldeneye vulnerable in places, continued study and conservation management will be needed to ensure both these goldeneyes continue gracing northern wetlands for generations to come.