Common Merganser Bird Facts (Mergus merganser)

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.

The Common Merganser is not typically found in Woodland habitats.

The Common Merganser is not typically found in Garden habitats.

The Common Merganser can be found in Wetland habitats.

The Common Merganser can be found in Coastal habitats.

The Common Merganser is not typically found in Urban habitats.

The Common Merganser is not typically found in Farmland habitats.

The Common Merganser is not typically found in Grassland habitats.

The Common Merganser is not typically found in Desert habitats.

The Common Merganser is not typically found in Tundra habitats.

The Common Merganser is not typically found in Rainforest habitats.

The Common Merganser is not typically found in Mountain habitats.

The Common Merganser is not typically found in Savanna habitats.

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.

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

Species that are present in the area during their breeding season

Afghanistan Kazakhstan Mongolia Russia Tajikistan United States of America Uzbekistan

Species that are present in the area outside their breeding season

Azerbaijan Belgium Bulgaria Hungary Iran Iraq Liechtenstein Luxembourg Netherlands Slovakia Spain Turkey

Species that appear infrequently (rare) and unpredictably outside their normal range

Algeria Cyprus Greenland Israel Malta Morocco Portugal Svalbard and Jan Mayen Islands Tunisia

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Bird 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.

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.

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.

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.

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.

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.

The Common Merganser typically lives for 8 years, with a maximum recorded lifespan of 14.8 years.

Like all birds, lifespan can be affected by factors including predation, habitat quality, disease, and access to food sources.

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.

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

Adult Common Mergansers face threats from large raptors like Bald Eagles and Great Horned Owls, while eggs and ducklings are vulnerable to raccoons, minks, and large fish.

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'.

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Bird Attributes Explained

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Understanding the Ratings:

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Adaptability

Aggressiveness

Endurance

Diet

Behaviour

Vocalisation

Nesting & Breeding

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Conservation and Status

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Population Data

Rarity Index

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