Common Merganser
Mergus merganser
Visual Identification
Appearance
The Common Merganser is a large, streamlined duck with a distinctive long, narrow bill. Males have a dark green head, white body, and black back, while females display a grey body with a rusty cinnamon head and white chin.
Both sexes have a bright red, serrated bill and orange legs. Juveniles resemble females but with a shorter crest and duller overall colouration.
Size
Length
58cm to 68cm
Wingspan
78cm to 94cm
Weight
1000g to 2.1kg
Habitat and Distribution
Habitats
Woodland
Garden
Wetland
Coastal
Urban
Farmland
Grassland
Desert
Tundra
Rainforest
Mountain
Savanna
Distribution
Common Mergansers inhabit clear, fish-rich freshwater bodies, including lakes, rivers, and reservoirs. They are found across northern North America, Europe, and Asia, with populations extending into more temperate regions.
Some birds move to coastal areas or larger unfrozen water bodies in winter. They are widespread in Canada, the northern United States, and parts of Europe, including the UK, where they are known as Goosanders.
Elevation Range
Sea level to 2,000 meters
Climate zones
Temperate, Subarctic
Distribution Map
This map gives you a rough idea of where you might spot a Common Merganser. The coloured areas show countries where these birds have been seen.
A few things to keep in mind:
- Birds might not be everywhere in the coloured areas, for example, they may be present around the coast of that country
- Where birds live can change with seasons and available food
- This map is quite simple - it doesn't show exact locations
We're working on making our maps even better! Soon, we hope to show you:
- More detailed maps for bigger countries, including state and region
- How birds move around during different seasons
Distribution by Region
Behaviour and Ecology
Bird Attributes
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Share your thoughtsBird Attributes Explained
Our bird attributes system rates various aspects of a bird's capabilities on a scale of 0-100, based on data from field observations, scientific studies, and expert knowledge.
Attribute Categories:
- Agility: Manoeuvrability, speed, and grace in flight or movement.
- Strength: Physical power, often correlating with size and hunting abilities.
- Adaptability: Ability to thrive in various environments or changing conditions.
- Aggressiveness: Territorial behaviour and assertiveness, particularly during breeding seasons.
- Endurance: Stamina, often seen in migration patterns or foraging behaviours.
Understanding the Ratings:
- 0-20: Very Low
- 21-40: Low
- 41-60: Average
- 61-80: High
- 81-100: Very High
Remember, these attributes are relative to other bird species and don't necessarily indicate superiority.
Hover over the icon next to each attribute for more information.
Tap the icon next to each attribute for more information.
Agility
Reflects the bird's manoeuvrability, speed, and grace in flight or movement.
The Common Merganser displays remarkable agility, particularly in aquatic environments. As excellent divers, they can manoeuvre swiftly underwater, staying submerged for up to 2 minutes whilst pursuing fish. Their streamlined body and powerful legs contribute to their impressive underwater agility.
Strength
Indicates the bird's physical power, often correlating with size and hunting abilities.
These large diving ducks possess considerable strength, evident in their ability to dive to depths of 9 metres and catch fish up to 30 cm in length. Their powerful legs propel them efficiently through water, and they can take off from water surfaces despite their size, indicating good muscular strength.
Adaptability
Represents the bird's ability to thrive in various environments or changing conditions.
Common Mergansers demonstrate high adaptability, thriving in various freshwater habitats from sea level to 2,000 metres elevation. Their ability to switch between freshwater and coastal environments, coupled with their partial migratory behaviour, showcases their adaptable nature. They've also adapted well to using artificial nest boxes when natural cavities are scarce.
Aggressiveness
Measures the bird's territorial behaviour and assertiveness, particularly during breeding seasons.
While not overtly aggressive, Common Mergansers display territorial behaviour during breeding season, with males performing elaborate courtship displays. They may engage in disputes over nesting sites or feeding areas. Their predatory nature in fishing also suggests a moderate level of assertiveness.
Endurance
Reflects the bird's stamina, often seen in migration patterns or foraging behaviours.
The endurance of Common Mergansers is evident in their long-distance migrations, diving capabilities, and ability to withstand cold temperatures in northern habitats. Their capacity to dive repeatedly for food and their widespread distribution across different climate zones indicate good stamina and resilience.
Diet
Common Mergansers primarily feed on fish, using their serrated bills to grip slippery prey. They also consume aquatic invertebrates, amphibians, and occasionally small mammals or birds. These efficient predators can consume fish up to 30 cm in length.
In the past, they have been targeted by commercial fish farms following their penchant for trout and salmon, although more commonly, they will feed on the more abundant species of fish available within their immediate habitat.
Behaviour
Common Mergansers are excellent divers, using their powerful legs to propel themselves underwater in pursuit of fish. They often form small flocks during winter and engage in cooperative fishing behaviour.
These birds are generally quiet but become more vocal during courtship displays.
Vocalisation
Common Mergansers are generally quiet outside the breeding season. During courtship and nesting, males produce soft, grunting calls, while females make a harsh, croaking sound.
Alarm calls consist of a low, grating 'karr-karr' that can be heard during territorial disputes.
Nesting & Breeding
Breeding begins in late winter or early spring, with pairs forming on wintering grounds. Males perform elaborate courtship displays, including head-pumping and wing-flapping.
Females typically nest in tree cavities near water, sometimes using artificial nest boxes. They lay 6-13 cream-coloured eggs in a down-lined nest.
Incubation lasts about 32 days and is performed solely by the female. Ducklings leave the nest within 24 hours of hatching, often jumping from considerable heights to reach water.
Conservation and Status
Global Conservation Status
While the Common Merganser is currently listed as Least Concern, it faces threats from habitat loss and degradation of freshwater ecosystems.
Conservation efforts focus on protecting water quality and maintaining healthy fish populations in their breeding and wintering areas.
Population Data
Global Population Estimate
1,700,000 - 2,400,000 mature individuals [2]
Global Population Trend
Trend data may be uncertain or fluctuating
Birdwatching Tips
- Look for them on clear, fish-rich lakes and rivers
- Observe their diving behaviour, as they can stay submerged for up to 2 minutes
- Listen for their soft, grunting calls during breeding season
- In North America, watch for them year-round in northern regions and during winter in southern areas
Additional Information
Quick Facts
Predators
Did You Know?
- Common Mergansers have over 100 sharp, backward-pointing projections on their bill to help grip fish.
- They can dive to depths of up to 30 feet (9 meters) in search of prey.
- Female mergansers sometimes lay eggs in each other's nests, a behaviour known as 'egg dumping'.
Similar Birds
References
- 1
website: BirdLife International. 2018. Mergus merganser. The IUCN Red List of Threatened Species 2018: e.T22680492A132054083.
View source - 2
report, 2015: Wetlands International
- 3
website, 2010: Fransson et al., EURING list of longevity records for European birds
View source
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