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Red-Breasted Merganser Vs Common Merganser: Differentiating Two Merganser Species

In the avian realm, the Red-breasted Merganser and the Common Merganser stand as captivating examples of adaptive diversity within the waterfowl family.

These two species, though sharing similarities in the overarching Merganser genus, exhibit distinct characteristics that have evolved in response to their habitats, behaviors, and ecological roles.

From their nesting behaviors and preferred wintering locations to their vocalizations and feeding habits, each species showcases a unique set of traits that contribute to their survival strategies.

Delving into the subtle differentiations between these two birds illuminates the intricate tapestry of nature’s adaptation and highlights the nuanced beauty within the avian world.

red breasted merganser vs common merganser

Key Differences Between Red-breasted Merganser and Common Merganser

Here’s a concise comparison highlighting the main differences between the Red-breasted Merganser and the Common Merganser:


  • Red-breasted Merganser: The Red-breasted Merganser finds its habitat in coastal regions, often favoring saltwater environments like coastal bays, estuaries, and marine coastlines. Its adaptation to marine ecosystems makes it well-suited for life along the saltwater shorelines.
  • Common Merganser: In contrast, the Common Merganser prefers a broader range of habitats. It thrives in freshwater environments such as lakes, rivers, and ponds, where its foraging behavior and nesting habits are well-aligned with the available resources.

Winter Habitat

  • Red-breasted Merganser: The Red-breasted Merganser showcases a distinct preference for wintering in saltwater environments.
    This species demonstrates remarkable adaptability to marine life, as it can be observed frequenting coastal waters and saltwater bodies during the colder months.
    Its physiology, including specialized salt glands that help eliminate excess salt, aids its survival in these habitats.
  • Common Merganser: Conversely, the Common Merganser exhibits a more varied winter habitat preference.
    Although it can tolerate saltwater, it predominantly seeks refuge in freshwater habitats during the winter season. Lakes, rivers, and ponds become its havens, where it find ample food sources and suitable conditions.

Nesting Behavior

  • Red-breasted Merganser: When it comes to nesting behavior, the Red-breasted Merganser showcases distinct characteristics. This species tends to build its nests on the ground, often in concealed locations that offer protection from predators.
    The choice of ground nesting is influenced by its coastal habitat, where suitable trees for cavity nesting might be limited.
  • Common Merganser: In contrast, the Common Merganser adopts a different approach to nesting. It favors tree cavities for nesting purposes.
    These cavities, often created by woodpeckers or naturally formed, provide the necessary protection and shelter for their young. The use of cavities keeps their eggs and ducklings safe from ground-based predators.

Nesting Locations

  • Red-breasted Merganser: The nesting locations of the Red-breasted Merganser reflect its preference for ground nesting. They select concealed spots near water bodies, such as grassy or wooded areas close to the shorelines.
    This choice of location ensures that the nests are well-hidden and provide the proximity to water that is essential for their survival.
  • Common Merganser: The Common Merganser, due to its affinity for cavity nesting, seeks out appropriate tree hollows for its nesting sites.
    These can be found both near water bodies and in inland areas. In regions where natural cavities are lacking, they readily adopt human-provided nest boxes, indicating their adaptability to changing landscapes.

Head Color (Males)

  • Red-breasted Merganser: One of the distinguishing features of male Red-breasted Mergansers is their red-brown heads adorned with a shaggy crest.
    This vibrant coloration is striking and aids in identifying this species. The color serves as a visual cue during courtship displays, and the shaggy crest adds to their distinct appearance.
  • Common Merganser: Male Common Mergansers, on the other hand, exhibit a dark green head that contrasts with their white bodies.
    This head coloration, while not as vibrant as that of the Red-breasted Merganser, is still distinctive and plays a role in attracting mates during their reproductive rituals.

Head Color (Females)

  • Red-breasted Merganser: Female Red-breasted Mergansers display a brownish-red head color, which helps them blend into their natural surroundings.
    This muted coloration provides camouflage and protection against potential predators, especially while they are engaged in nesting and rearing activities near water bodies.
  • Common Merganser: Female Common Mergansers exhibit a similar brownish-red head color as well. Like their Red-breasted counterparts, this subtle hue contributes to their overall survival strategy.
    By blending into their environment, they can safeguard their nests and young ducklings, which are particularly vulnerable during the nesting season.

Body Color (Males)

  • Red-breasted Merganser: The white body of the male Red-breasted Merganser stands out distinctly against its red-brown head and gray back. This striking contrast in coloration is a key feature that aids in visual identification.
    The white body serves as a canvas against which the vibrant head color and other features become even more prominent, making them recognizable at a glance.
  • Common Merganser: In contrast, the male Common Merganser features a white body as well. This shared characteristic with the Red-breasted Merganser underscores their common lineage.
    However, unlike the Red-breasted Merganser, the Common Merganser does not exhibit the same level of contrast between head and body coloration, allowing its distinct dark green head to take center stage.

Body Color (Females)

  • Red-breasted Merganser: The gray body of female Red-breasted Mergansers provides effective camouflage in their coastal habitat.
    The subdued color helps them blend into the surroundings, particularly when they are incubating eggs or leading their young ducklings to the water. This adaptive coloration minimizes their vulnerability to predation during crucial life stages.
  • Common Merganser: Female Common Mergansers also possess a gray body color that contributes to their protective camouflage.
    This shared trait with the Red-breasted Merganser highlights their parallel strategies for survival and successful reproduction. The gray body serves as an inconspicuous backdrop that assists in their vital roles within the ecosystem.

Back Color (Males)

  • Red-breasted Merganser: The gray back of male Red-breasted Mergansers complements their overall color palette. This muted back coloration, combined with their vibrant head and white body, forms a visually appealing combination.
    While the back color is less attention-grabbing, it contributes to the bird’s balanced appearance and ensures that the striking head color remains the focal point.
  • Common Merganser: In the case of the male Common Merganser, specific information about back coloration is not highlighted as prominently as in the Red-breasted Merganser.
    However, it’s important to note that these males also have grayish backs, aligning with the coloration that provides effective camouflage in their preferred habitats.

Bill Color (Males)

  • Red-breasted Merganser: The male Red-breasted Merganser boasts a dark bill with a lighter base. This coloration variation in the bill is not only an identifying feature but also serves functional purposes.
    The bill’s design facilitates efficient foraging, aiding in capturing fish, their primary diet. The darker color helps hide stains that might accumulate from their aquatic feeding habits.
  • Common Merganser: Male Common Mergansers exhibit a different bill coloration. Their bills are distinctly red, which stands out against their dark green heads.
    This red bill, along with their overall appearance, contributes to their attractiveness during courtship displays and plays a role in mate selection.

Bill Color (Females)

  • Red-breasted Merganser: The bill color of female Red-breasted Mergansers mirrors that of their male counterparts: dark with a lighter base. This shared bill coloration suggests an evolutionary adaptation that supports their piscivorous feeding habits.
    The dark bill aids in grasping and capturing fish, their primary food source, while the lighter base potentially helps in camouflaging any debris or staining that may occur during feeding.
  • Common Merganser: Female Common Mergansers also possess a similar bill coloration – dark with a lighter base. Like the Red-breasted Merganser females, this bill design is well-suited for their fish-focused diet.
    The consistency in bill coloration between the two species underlines the importance of efficient foraging strategies in their survival.

Preferred Nest Type

  • Red-breasted Merganser: The Red-breasted Merganser exhibits a preference for ground nests, choosing concealed locations near water bodies for nesting purposes.
    This adaptation aligns with their coastal habitat, where access to suitable tree cavities for nesting might be limited. Ground nesting ensures proximity to water, which is crucial for the survival of both nests and ducklings.
  • Common Merganser: In contrast, the Common Merganser favors a different nesting approach. It tends to utilize tree cavities for nesting, often selecting natural hollows created by woodpeckers.
    Additionally, they can adapt to man-made nest boxes, showcasing their ability to exploit various resources in their environment for successful reproduction.

Preferred Wintering Locations

  • Red-breasted Merganser: The Red-breasted Merganser displays a clear preference for wintering in saltwater habitats.
    Their adaptation to marine environments allows them to thrive in coastal bays, estuaries, and marine coastlines. The ability to utilize saltwater for wintering highlights their specialization for life near the sea.
  • Common Merganser: On the other hand, the Common Merganser’s wintering behavior leans more toward freshwater habitats.
    While it can tolerate saltwater, it primarily seeks refuge in freshwater bodies such as lakes, rivers, and ponds. This adaptability showcases their flexibility in exploiting various types of water sources for survival.


  • Red-breasted Merganser: The range of the Red-breasted Merganser encompasses northern regions, often nesting farther north than the Common Merganser.
    Their distribution extends across specific coastal areas in North America and Eurasia, where their affinity for saltwater habitats becomes particularly pronounced.
  • Common Merganser: The Common Merganser shares a similar range with the Red-breasted Merganser, covering northern regions in North America and Eurasia.
    However, their range might be slightly broader compared to the Red-breasted Merganser, allowing them to inhabit a wider variety of freshwater habitats beyond coastal areas.

Habitat Range

  • Red-breasted Merganser: Red-breasted Mergansers demonstrate a specialized habitat range, favoring coastal environments. They thrive in coastal bays, estuaries, and marine coastlines, reflecting their adaptation to saltwater conditions and marine ecosystems.
  • Common Merganser: The Common Merganser’s habitat range is more versatile, encompassing both freshwater and saltwater environments. While they are more inclined toward freshwater habitats such as lakes, rivers, and ponds, they can adapt to saltwater conditions if necessary.


  • Red-breasted Merganser: The Red-breasted Merganser is superbly adapted to marine environments. Its physiology, including specialized salt glands, enables it to thrive in coastal and saltwater habitats. This adaptation allows it to regulate its salt balance effectively and exploit the resources available in the marine ecosystem.
  • Common Merganser: While the Common Merganser is not as specialized for marine life as the Red-breasted Merganser, it has a versatile adaptation to both freshwater and saltwater environments. Its ability to utilize different water sources showcases its adaptability and resilience.


  • Red-breasted Merganser: Male Red-breasted Mergansers possess a distinctive shaggy crest that adds to their charismatic appearance. This crest, along with their vibrant red-brown head, is a key component of their courtship display and communication with potential mates.
  • Common Merganser: The Common Merganser does not exhibit a prominent crest in males. While the absence of a crest does not diminish their elegance, it marks a visual difference from the Red-breasted Merganser’s appearance.


  • Red-breasted Merganser: The Red-breasted Merganser tends to be slightly smaller in size compared to the Common Merganser. This difference in size, though subtle, can contribute to variations in behavior, habitat utilization, and ecological interactions.
  • Common Merganser: The Common Merganser is slightly larger in size when compared to the Red-breasted Merganser. This size distinction can influence their interactions with other species, as well as their overall foraging habits and strategies.

Feeding Habits

  • Red-breasted Merganser: Red-breasted Mergansers have a specialized diet primarily focused on fish. Their slender bills are well-suited for capturing and consuming aquatic prey, aligning with their coastal and marine habitat preferences.
  • Common Merganser: The Common Merganser shares the fish-focused feeding habit with the Red-breasted Merganser. Their adaptations for efficient fish capture make them effective predators in freshwater environments, where fish are abundant.


  • Red-breasted Merganser: The Red-breasted Merganser is recognized for its distinctive high-pitched calls. These calls play a role in communication during various situations, such as courtship, territorial disputes, and interactions with other individuals.
  • Common Merganser: The Common Merganser also possesses distinctive calls, contributing to its vocal repertoire for communication. The variety of calls serves purposes ranging from social interactions to warning signals.


  • Red-breasted Merganser: Red-breasted Mergansers exhibit agile diving behavior, enabling them to efficiently pursue and capture fish underwater. They are skilled swimmers, using their adaptations for aquatic life to their advantage.
  • Common Merganser: The Common Merganser shares the same agile diving behavior as the Red-breasted Merganser. Their strong swimming abilities make them efficient predators in both freshwater and saltwater environments.

Red Breasted Merganser Vs Common Merganser: Comparison Table

AspectRed-breasted MerganserCommon Merganser
HabitatCoastal, saltwater environmentsFreshwater habitats, lakes, rivers, ponds
Winter HabitatSaltwater bodiesFreshwater bodies
Nesting BehaviorGround nestsTree cavities, natural or man-made
Nesting LocationsNear water bodiesNear water bodies or inland areas
Head Color (Males)Red-brown with shaggy crestDark green
Head Color (Females)Brownish-redRusty
Body Color (Males)WhiteWhite
Body Color (Females)GrayGray
Back Color (Males)Gray
Bill Color (Males)Dark with light baseRed
Bill Color (Females)Dark with light baseReddish
Preferred Nest TypeGround nestsTree cavities or nest boxes
Preferred Wintering LocationsSaltwaterFreshwater
RangeNorthern regionsNorthern regions with a slightly broader range
Habitat RangeCoastal bays, estuaries, marine coastlinesLakes, rivers, ponds
AdaptationMarine environmentsFreshwater habitats
CrestPresent in males
SizeSlightly smallerSlightly larger
Feeding HabitsFish-focusedFish-focused
VoiceHigh-pitched callsDistinctive calls
BehaviorAgile divers, fast swimmersSkilled divers, strong flyers

Frequently Asked Questions

How do the nesting behaviors of Red-breasted Mergansers and Common Mergansers impact their habitat selection?

Nesting behaviors influence where these ducks establish their homes. Red-breasted Mergansers opt for ground nests due to limited cavity options near water, while Common Mergansers use tree cavities. This choice shapes their habitat preferences – Red-breasted near coastal areas and Common near water bodies with trees.

What distinguishes the vocalizations of Red-breasted Mergansers from those of Common Mergansers?

Red-breasted Mergansers are known for their high-pitched calls that serve various purposes in communication. In contrast, Common Mergansers possess a range of distinct calls used for interactions and signaling. Their vocalizations reflect their unique social dynamics and behaviors within their habitats.

How does the presence of a crest in male Red-breasted Mergansers impact their reproductive success?

The shaggy crest in male Red-breasted Mergansers plays a role in courtship displays and mate selection. A prominent crest can indicate health and vitality, influencing female mate choice. Males with more elaborate crests might have a competitive advantage in attracting mates and contributing to successful reproduction.

What advantages do the specialized bills of female Mergansers provide for their fish-focused feeding habits?

The dark bills with lighter bases in female Mergansers are adapted for capturing fish. The dark coloration helps conceal debris and stains from their piscivorous diet, maintaining their hunting efficiency. The bill’s shape and serrated edges aid in grasping and securing slippery prey underwater.

How do the wintering preferences of Red-breasted Mergansers and Common Mergansers contribute to their survival strategies?

Red-breasted Mergansers’ affinity for saltwater wintering is a result of their adaptation to marine environments, allowing them to thrive in coastal waters. Common Mergansers’ choice to winter in freshwater habitats highlights their versatility, utilizing resources available in various types of water bodies for their survival during colder months.

To Recap

The Red-breasted Merganser and the Common Merganser exemplify the remarkable diversity and adaptability present in avian species.

Their contrasting features, from bill coloration and nesting preferences to vocalizations and behavior, underscore the intricate ways in which nature molds species to fit their respective niches.

Through these differences, these ducks have harnessed unique strategies for thriving in their environments.

The exploration of their characteristics not only deepens our understanding of avian biology but also emphasizes the importance of biodiversity in sustaining the delicate balance of ecosystems.

The Red-breasted and Common Mergansers serve as living reminders of the boundless wonders of the natural world.

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