Common Merganser (Mergus merganser) lives in freshwater rivers lakes across Europe, northern and central Asia, and North America. Its conservation status is Least Concern.
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The common merganser's bill is fitted with tiny serrations that work like a saw, allowing it to seize slippery fish with a firm grip. This specialised edge is the reason waterbird enthusiasts refer to the species as a "sawbill". Measuring 58-72 cm in length and weighing up to 2.1 kg, the duck relies on this tool for its primarily piscivorous diet. Its red-to-brown bill, brightest in adult males, highlights the adaptation that makes it such an effective hunter.
When feeding, common mergansers often assemble in a loose semicircle, driving schools of fish toward the shallows where the prey become easier to catch. This coordinated herding boosts the group's capture success and is accompanied by their low, harsh croak that can signal the start of the maneuver. One or more individuals keep watch, ready to warn the flock of danger, while the rest plunge their saw-bills into the concentrated fish.
Female common mergansers lay between six and seventeen eggs, most often eight to twelve, and after hatching they carry the ducklings on their backs to nearby water where the young feed on invertebrates and tiny fish. In some colonies a single mother has been recorded supervising a crèche of over seventy ducklings, a remarkable gathering for a species that normally raises one brood per season.
Most Western European male common mergansers head north each summer to moult in the Finnmark estuaries of northern Norway, chiefly at Tanafjord. They depart the breeding sites as soon as the ducklings hatch and spend the June-September period elsewhere, leaving the nest behind. The females remain on the breeding grounds, solely responsible for feeding and protecting the young until they fledge.
In larger streams and rivers, common mergansers let the current carry them downstream for a few miles before turning back. Rather than immediately taking to the air, they usually swim back upstream, using powerful strokes that keep them submerged like cormorants. When they are not actively diving, they may float on the surface, alternating between surface drifting and deep underwater propulsion.
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RangeEurope, northern and central Asia, and North America
HabitatFreshwater rivers lakes
DietFish and crustaceans
About the Common Merganser
In the dappled light of a forest stream, the Common Merganser glides with effortless elegance, its sleek, sawbill profile slicing through the water as it pursues the aquatic delicacies that sustain it. With a flick of its tail and a soft whoosh of its wings, this charismatic duck navigates the winding waterways with a fluidity that belies its size, its feathers glistening like polished ebony and amber in the sun's gentle rays. As it dives and weaves through the submerged vegetation, the merganser's remarkable adaptability and agility are on full display, a testament to its enduring presence in these tranquil, aquatic realms.
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