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King Eider Vs Common Eider: A Comparative Study of Eider Duck Species

The King Eider and Common Eider are captivating sea duck species that inhabit the northern reaches of our planet. These avian wonders share similarities as members of the same genus, yet exhibit distinct characteristics that set them apart.

From their physical attributes and behaviors to their preferred habitats and interactions with humans, the King Eider and Common Eider showcase the remarkable diversity within the avian world.

Exploring their differences offers insights into their evolutionary adaptations and ecological roles. In the following discussion, we delve into their unique traits, shedding light on the intricacies that define these remarkable waterfowl species.

king eider vs common eider

Key Differences Between King Eider and Common Eider

Here are some key differences between the king eider and vs common eider:

Head Shape

  • King Eider: The head of female King Eiders exhibits a unique roundness, accentuated by an upturned line at the bill. This distinctive feature imparts a grinning expression, setting them apart. This rounded head is a key characteristic, contributing to the visual identification of female King Eiders.
  • Common Eider: In contrast, female Common Eiders display a head with a long and sloping forehead. Unlike the King Eiders, they lack the upturned bill line and grinning expression.
    This distinction in head shape aids in distinguishing between these two species, particularly in terms of their facial characteristics.

Coloration (Male)

  • King Eider: The male King Eider boasts a striking and vibrant coloration. It exhibits a remarkable blend of black, white, and pale blue hues on its body.
    Its most distinct feature is the captivating green nape that sets it apart from other sea ducks. This rich combination of colors makes the male King Eider a standout specimen in its habitat.
  • Common Eider: On the other hand, the male Common Eider displays a predominantly black body, adorned with a large white patch on its sides.
    This stark black-and-white contrast, along with the absence of the vivid blue and green tones seen in the King Eider, contributes to its own unique and recognizable appearance.

Coloration (Female)

  • King Eider: Female King Eiders exhibit a more muted color palette, characterized by brown tones with mottled patterns. This camouflage-like appearance serves to blend them into their tundra nesting environment, providing effective protection from potential predators.
  • Common Eider: Similarly, female Common Eiders also sport brown plumage with mottled patterns. This earth-toned coloring aids in their concealment within coastal and marine habitats, helping them evade threats and go unnoticed while nesting.


  • King Eider: King Eiders can be found inhabiting the Arctic and subarctic regions, particularly coastal areas. They breed in the Arctic tundra, taking advantage of its nesting resources, and migrate southward for the winter season to find suitable marine habitats.
  • Common Eider: Common Eiders are distributed across northern coastal regions, where they thrive in both marine and brackish waters. They have a notable presence in areas such as North America, Europe, and Asia. Unlike the King Eiders, Common Eiders tend to migrate shorter distances during the winter months.

Bill Shape

  • King Eider: The King Eider features a stout bill with a slightly upturned line at the tip. This billing structure is well-suited for its feeding habits, which primarily involve foraging for marine invertebrates and small prey beneath the water’s surface.
  • Common Eider: In contrast, the Common Eider possesses a stout bill with a medium length. This bill design is tailored to its own feeding behavior, which involves diving for mollusks, crustaceans, and sea urchins in the marine environment.

Facial Expression

  • King Eider: Among the key distinctions between the King Eider and the Common Eider is the facial expression of the female King Eider. Females of this species possess a unique and intriguing feature: a rounder head shape with an upturned line at the bill.
    This configuration gives them a grinning or smiling appearance. This distinctive trait is not observed in their Common Eider counterparts and serves as a recognizable marker for identifying King Eiders.
  • Common Eider: In contrast, female Common Eiders have a different head shape characterized by a longer and sloping forehead. Unlike the King Eiders, they lack the upturned line at the bill, which contributes to the distinct facial expressions seen in their counterparts.


  • King Eider: In terms of size, King Eiders are slightly smaller when compared to Common Eiders. This size difference is often observable when the two species are seen together, with the King Eider appearing marginally smaller in stature.
  • Common Eider: The Common Eider, being slightly larger in size than the King Eider, presents a noticeable contrast when it comes to the physical dimensions of these two species. This size disparity can contribute to differentiation during observations in their natural habitats.


  • King Eider: The range of the King Eider is primarily focused on Arctic and subarctic regions. During breeding seasons, these birds can be found in Arctic coastal areas, utilizing the tundra for nesting. They undertake significant migrations, journeying southward to more temperate waters for the winter.
  • Common Eider: Conversely, the Common Eider has a broader range that spans across the northern coasts of North America, Europe, and Asia.
    While they also inhabit Arctic and subarctic regions, their winter migration distances are comparatively shorter than those of the King Eider.


  • King Eider: Male King Eiders are known for their intricate and captivating plumage. With a mix of black, white, and pale blue colors, highlighted by a vibrant green nape, they possess a striking appearance. This distinct color combination sets them apart from other sea ducks and plays a role in courtship displays.
  • Common Eider: The male Common Eider exhibits a simpler black-and-white plumage. The most prominent feature is the large white patch on their sides. This plumage design provides them with a classic, crisp look that distinguishes them within their habitat.

Nesting Habits

  • King Eider: King Eiders exhibit specific nesting habits that align with their Arctic habitat. They nest in the Arctic tundra, using the natural surroundings to create well-camouflaged nests. These nests are strategically positioned to offer protection and warmth to their eggs during the breeding season.
  • Common Eider: Female Common Eiders share a similar nesting strategy. They typically create nests in coastal areas, constructing them from down feathers.
    These nests are often situated close to water bodies, allowing for convenient access to food sources and minimizing the vulnerability of their offspring to predators.


  • King Eider: The vocalizations of King Eiders are characterized by a range of sounds that include whistling and low growls. These vocal cues play a role in communication during various contexts, such as mating rituals and interactions among flock members.
    The complexity of their vocalizations contributes to their ability to convey information within their social groups.
  • Common Eider: Conversely, Common Eiders communicate using a variety of calls that serve different purposes.
    These calls help them maintain contact with each other while foraging or during flight. The sounds they emit are tailored to their social interactions and the challenges they encounter in their marine environments.

Feeding Habits

  • King Eider: King Eiders primarily feed on marine invertebrates, including mollusks, crustaceans, and other aquatic organisms.
    Their stout, slightly upturned bills are well-suited for diving and foraging beneath the water’s surface, allowing them to efficiently access their preferred food sources.
  • Common Eider: The Common Eider’s feeding habits revolve around diving for various marine prey, including mollusks, crustaceans, and sea urchins.
    Their stout, medium-length bills are adapted to capture and consume these underwater delicacies, helping them thrive in their coastal habitats.

Migratory Behavior

  • King Eider: King Eiders are long-distance migrants. They cover significant distances during their migrations, often traveling from their breeding grounds in the Arctic to more temperate waters for the winter. This migratory behavior reflects their adaptability to different environments and their ability to navigate challenging conditions.
  • Common Eiders: Common Eiders also exhibit migratory behavior, but their migrations are generally shorter in comparison to those of King Eiders.
    They move from northern breeding areas to wintering locations that offer suitable marine habitats. This migratory pattern aligns with their range and ecological preferences.

Social Behavior

  • King Eider: During migration and wintering periods, King Eiders are known to form large flocks. These flocks consist of individuals coming together for various reasons, including protection, foraging efficiency, and social interactions. The formation of these flocks showcases the importance of social dynamics in their survival strategies.
  • Common Eider: Common Eiders exhibit a different social behavior, often seen in smaller groups rather than large flocks.
    These smaller gatherings are believed to provide advantages in terms of foraging and protection, allowing individuals to efficiently navigate their coastal and marine habitats.

Breeding Displays

  • King Eider: Male King Eiders engage in elaborate courtship displays to attract females during the breeding season. These displays involve a combination of visual cues, vocalizations, and physical movements that demonstrate the male’s fitness and readiness to mate.
    These displays play a significant role in the selection of mates and contribute to the continuation of their species.
  • Common Eider: Similarly, male Common Eiders also participate in courtship displays that involve visual and vocal elements. These displays are designed to capture the attention of potential mates and demonstrate the male’s suitability as a partner.
    The specific behaviors and rituals within these displays can vary among individuals and populations.

Population Status

  • King Eider: The population of King Eiders is generally stable, and they are not considered globally threatened.
    Their ability to thrive in Arctic and subarctic regions, along with their adaptability to varying conditions, contributes to their relatively stable population status.
  • Common Eider: Similarly, the Common Eider is not globally threatened and often maintains stable populations. While local variations and pressures can impact their numbers, these ducks have managed to sustain themselves in their diverse range of habitats.

Preferred Waters

  • King Eider: King Eiders are often observed in both nearshore and offshore waters. Their presence is notable in marine environments, where they engage in feeding, migration, and various other activities.
  • Common Eider: Common Eiders inhabit a range of waters, including saltwater and brackish areas. They are commonly found in coastal regions, taking advantage of the resources offered by both marine and estuarine ecosystems.

Conservation Status

  • King Eider: As of the current assessment, King Eider is not considered globally threatened. However, localized threats such as habitat degradation, pollution, and disturbances could impact specific populations.
  • Common Eider: Similar to the King Eider, the Common Eider is not globally threatened. Nevertheless, the species can face localized threats, including disturbances caused by human activities, habitat loss, and changing environmental conditions.


  • King Eider: In some regions, King Eiders have been hunted for subsistence and sport. While regulations and conservation efforts are in place to manage hunting sustainably, these practices can impact local populations.
  • Common Eider: Historically, Common Eiders have been hunted for their eiderdown, a valuable insulating material found in their nests.
    This practice has led to the conservation concern of disrupting nesting activities and affecting local populations. Modern conservation measures aim to balance these practices.

Physical Characteristics

  • King Eider: Male King Eiders are characterized by intricate patterns and vivid colors, including black, white, pale blue, and a distinctive green nape. These features are essential for mate attraction and courtship displays, showcasing their fitness and genetic quality.
  • Common Eider: Male Common Eiders display a simpler black-and-white plumage with a striking white patch on their sides. Their appearance may be less vibrant compared to King Eiders, but it serves their own specific functions in both courtship rituals and camouflage.

King Eider Vs Common Eider: Comparison Table

AspectKing EiderCommon Eider
Head ShapeFemales have a rounder head with an upturned bill line, giving them a grinning expression.Females have a longer, sloping forehead.
Coloration (Male)Variable populations; are not globally threatened.Mostly black body with a large white patch on the sides.
Coloration (Female)Muted brown with mottled patterns for camouflage.Brown with mottled patterns.
HabitatFound in northern Arctic and subarctic regions.Inhabits northern coastal and marine areas.
Bill ShapeStout, slightly upturned bill.Stout, medium-length bill.
Facial ExpressionFound in the northern Arctic and subarctic regions.No distinct grinning expression.
SizeSlightly smaller than Common Eider.Slightly larger in size.
RangeBreeds in Arctic coastal areas; winters farther south.Found across northern coasts; migrates south in winter.
PlumageMales have intricate patterns and colorful plumage.Males have simpler black-and-white plumage.
Nesting HabitsNests in Arctic tundra regions.Females often exhibit a grinning or smiling expression due to upturned bills.
VoiceVocalizations include whistling and low growls.Communicates using various calls.
Feeding HabitsFeeds primarily on marine invertebrates.Dives for mollusks, crustaceans, and sea urchins.
Migratory BehaviorLong-distance migrant, covering significant distances during migration.Migrates shorter distances during winter.
Social BehaviorCan form large flocks during migration.Often seen in smaller groups.
Breeding DisplaysMales display courtship behaviors to attract females.Engages in elaborate courtship displays.
Population StatusGenerally stable, not globally threatened.Variable populations; not globally threatened.
Preferred WatersOften seen in nearshore and offshore waters.Inhabits both saltwater and brackish areas.
Conservation StatusNot globally threatened, but local threats exist.Generally not threatened, but local issues may impact populations.
HuntingHunted for subsistence and sport in some areas.Historical hunting for eiderdown and meat.
Physical CharacteristicsRounded body shape; distinct sexual dimorphism.Rounded body shape; less pronounced dimorphism.

Frequently Asked Questions

What Are the Key Differences in Breeding Behaviors Between King Eider and Common Eider?

Both species engage in courtship displays, but King Eider’s display is often more intricate and involves a combination of visual cues, vocalizations, and movements.
This display helps attract females by showcasing the male’s fitness and readiness to mate. Common Eiders also participate in courtship displays, but the specifics can vary among individuals and populations.

How Do King Eiders and Common Eiders Adapt to Their Respective Wintering Environments?

King Eiders undertake long-distance migrations, traveling from Arctic breeding grounds to temperate waters for the winter.
In contrast, Common Eiders migrate shorter distances to find suitable wintering locations. These adaptations allow them to find food resources and navigate varied winter conditions.

What Are the Distinct Nesting Characteristics of King Eiders and Common Eiders?

King Eiders nest in Arctic tundra regions, utilizing the natural surroundings for well-camouflaged nests.
Common Eiders construct nests in coastal areas using down feathers. These nests are often located near water bodies, providing easy access to food and minimizing predation risks.

How Do King Eider and Common Eider Females Differ in Appearance During Breeding Seasons?

Female King Eiders display a unique grinning expression due to their rounder head shape and upturned bill line. Female Common Eiders lack this feature and have a longer, sloping forehead.
Additionally, the coloration of female King Eiders is characterized by brown tones with mottled patterns, while female Common Eiders have similar brown plumage.

What Are the Conservation Challenges Faced by King Eiders and Common Eiders?

While neither species is globally threatened, both King Eiders and Common Eiders can be affected by local threats such as habitat degradation, pollution, and disturbances.
The historical practice of harvesting eiderdown from Common Eider nests has raised conservation concerns due to potential disruptions in nesting activities. Conservation efforts focus on managing these challenges to ensure the continued well-being of these duck species.

To Recap

The King Eider and Common Eider exemplify nature’s ability to craft intricate variations within species that share a common ancestry.

Their diverse physical attributes, behaviors, and adaptations highlight the remarkable ways in which these birds have evolved to thrive in distinct environments.

While both species contribute to the rich tapestry of coastal and marine ecosystems, their unique characteristics underscore the importance of biodiversity.

As we continue to study and appreciate these sea ducks, we gain deeper insights into the delicate balance of life in diverse habitats, motivating us to preserve and protect these remarkable avian wonders for generations to come.

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