Overview
The Common Eider (Somateria mollissima) is a large sea duck known for its bulky shape and large wedge-shaped bill. These birds are predominantly found in the northern coasts of Europe, North America, and eastern Siberia, where they prefer cold, coastal waters. Male Common Eiders are striking with black and white plumage and a green nape, while females are brown and well-camouflaged. Known for their down feathers, these birds have been historically harvested for their insulating properties, which are still valued in some regions today.
The Common Eider is a strong diver, often submerging to depths up to 20 meters to feed on sea life, including crustaceans, mollusks, and various sea invertebrates. During the breeding season, eiders are found in coastal areas, where they nest in colonies on islands or secluded shores. The species is also known for its unique ‘cooperative breeding’ behavior, where females may help each other by looking after nests. Outside the breeding season, they form large flocks on the sea, often mixing with other diving ducks.
Conservation efforts for the Common Eider focus on protecting breeding habitats and managing hunting pressures. Threats to their populations include oil spills, habitat loss, and increased disturbance in breeding areas. Despite these challenges, the Common Eider generally maintains a large global population, although some regional declines have been noted. The species is an important indicator of marine ecosystem health, reflecting changes in their food supply and habitat conditions.
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Physical Description:
The Common Eider is notable for its large size, heavy build, and distinctive wedge-shaped bill. During the breeding season, males are particularly striking with their contrasting black and white plumage and greenish nape, while females and non-breeding males are mottled brown. These birds possess a thick layer of down, which traps air and provides exceptional insulation, a critical adaptation for their cold-water habitats.
Adult Common Eiders are among the largest of ducks in size. Males typically weigh between 4.4 and 6.6 lbs (2 to 3 kg), while females weigh slightly less. The average length ranges from 20 to 28 inches (50 to 71 cm), with males slightly larger than females. Their wingspan is substantial, aiding in their powerful flight, stretching from 35 to 43 inches (89 to 109 cm).
Lifespan: Wild: ~20 Years || Captivity: ~25 Years
Weight: Male: 4.4-6.6 lbs (2-3 kg) || Female: 3.3-5.5 lbs (1.5-2.5 kg)
Length: Male: 22-28 inches (56-71 cm) || Female: 20-26 inches (50-66 cm)
Wingspan: Male & Female: 35-43 inches (89-109 cm)
Top Speed: 47 mph (76 km/h)
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Native Habitat:
The Common Eider is naturally found in the cold northern coasts of Europe, North America, and eastern Siberia. These birds prefer coastal marine environments, particularly in areas with a combination of rocky shores, islets, and sheltered inlets. They breed on isolated coastal islands or along the mainland coast where predation risk is minimal, and they have access to suitable nesting sites.
Outside the breeding season, Common Eiders migrate to more open sea areas, often forming large flocks in rich feeding zones. These winter habitats are typically near shallow waters where diving for food is accessible, but they can also be found in deeper waters. Food availability and suitable resting and nesting areas largely influence the birds’ habitat choice.
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Diet & Feeding Habits:
The Common Eider is primarily a predatory bird, adopting a diet around various marine organisms. They are proficient divers, often diving to considerable depths to forage for mollusks, crustaceans, and sea urchins, which they swallow whole. The birds’ large, powerful bills are adapted to prying open shellfish and marine invertebrates.
Feeding occurs mainly in shallow coastal waters where these birds dive and walk along the sea bottom to find food. During breeding season, they may consume more plant material, including seaweeds and aquatic plants. Feeding flocks can often be seen offshore, where birds work cooperatively to herd and catch prey. Their foraging efficiency is crucial, especially during the harsh winter months when food is scarce.
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Mating Description:
The Common Eider has a fascinating mating system characterized by complex social structures and behaviors. Males are polygynous, competing for territories and attracting females with their striking plumage and displays. Once a male has secured a mate, he guards her fiercely until she lays her eggs, after which he may leave to find another mate.
Females are solely responsible for nest building and incubation, often nesting in colonies for increased protection. The nests are built near the shoreline, using vegetation and lined with the females’ down. After the ducklings hatch, mothers often lead them to water and join ‘creches’ – groups of females and their young that provide safety in numbers. Reproduction is timed to coincide with the peak availability of food in their marine habitats.
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Social Structure Description:
The social structure of the Common Eider varies seasonally. During breeding, males display territorial behavior, competing for mates and defending nesting areas. Females are more social, often nesting near each other for added protection against predators. Once the breeding season is over, eiders form large flocks on the sea, showing less territoriality and more cooperative behavior.
In winter, these flocks can number in the thousands, providing safety in numbers and increasing foraging efficiency. Within these flocks is a loose social hierarchy, with dominant individuals often gaining access to the best feeding areas. The social structure of the Common Eider is complex and adaptable, allowing them to thrive in their dynamic coastal environments.
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Population:
The global population of the Common Eider is large, with hundreds of thousands of individuals across its range. However, regional populations can vary significantly, with some showing stable numbers and others experiencing declines. Factors contributing to population changes include hunting pressures, oil spills, predation, and loss of suitable habitat.
The Common Eider’s conservation efforts focus on protecting critical habitats, regulating hunting, and mitigating other human impacts like oil spills and disturbance. Monitoring population trends is crucial to understanding the species’ health and implementing effective conservation strategies. In some areas, recovery efforts have been successful, leading to stabilized or increasing populations, while other regions continue to face challenges.
Population Threats:
The Common Eider faces several threats, primarily from human activities. Oil pollution is a significant threat, as oil spills can lead to direct mortality and long-term habitat degradation. Overharvesting eggs and adult birds for food and down feathers has historically reduced populations in some areas and, while regulated, still threatens others.
Habitat loss and disturbance from coastal development, shipping, and recreational activities can disrupt breeding and foraging areas. Climate change also poses a long-term threat, potentially affecting the distribution and abundance of their prey and altering their marine and coastal habitats. Conservation efforts aim to mitigate these threats through habitat protection, regulations, and public awareness campaigns.
Conservation Efforts:
Conservation efforts for the Common Eider include legal protections, habitat management, and research. Many countries have implemented hunting regulations and protected areas to safeguard critical breeding and wintering sites. International agreements like the African-Eurasian Waterbird Agreement also provide a framework for conserving migratory waterbirds like the eider.
Research and monitoring are crucial for understanding population trends and the impacts of threats. Conservationists and researchers work to track changes in numbers, study the birds’ ecology, and assess the effectiveness of management actions. Public education campaigns aim to raise awareness about the species and promote responsible behavior in critical habitats.
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Fun Facts
- The down of the Common Eider is considered the warmest and most insulating in the world and is still harvested sustainably in some areas.
- Despite their heavy build, Common Eiders are agile divers, capable of reaching depths up to 20 meters.
- Female eiders are known for their ‘egg dumping’ behavior, where they lay eggs in the nests of other females, a form of cooperative breeding.
- The male’s dramatic change from the striking breeding plumage to the duller non-breeding colors is one of the most drastic among birds.
- Eider ducklings are born with a special coat that makes them highly buoyant, an essential adaptation for their aquatic life.
- The species’ name ‘Bellissima’ means ‘softest,’ referring to their down feathers.
- Common Eiders are the largest ducks in the Northern Hemisphere.
- They have a unique crooning call often heard in their breeding colonies.
- Conservation efforts for the eider have been successful in some areas, leading to stabilized populations.
- The Common Eider is the national bird of Iceland.
