The common merganser is a master of the river, equipped with a serrated bill.

Countries & Cities · Published 10 October 2026 Swipe more like this →

In short: Known as the goosander in Eurasia, this large, streamlined duck is a specialized fish-hunter. Unlike typical ducks with wide, flat bills, the merganser sports a narrow, serrated beak designed to grip slippery prey. These birds are equally at home on freshwater rivers and lakes or occasionally in coastal saltwater estuaries.

The common merganser, or Mergus merganser, is a large, long-bodied duck characterized by its distinctive appearance. Adult males display gleaming white bodies and iridescent-green heads, while females and immatures are gray-bodied with rusty-cinnamon heads and shaggy crests. Their specialized bills, which feature serrated edges, have earned them the nickname 'sawbills.' These serrations are essential for capturing their primary diet of fish, though they also consume crustaceans, molluscs, worms, and amphibians. In some cases, the salmon-pink tinge observed on the bodies of males is believed to be derived from carotenoid pigments found in their diet.

These ducks are primarily cavity nesters, typically utilizing hollow trees in northern forests. However, in treeless environments like the mountains of Central Asia, they adapt by nesting in cliff holes or steep banks. A female typically lays between 6 and 17 eggs. Once hatched, the ducklings are often carried on the mother's back to the water. The species is highly social, sometimes forming large crèches where a single female may be observed with over 70 ducklings. They are also known for cooperative hunting, where groups form semicircles to drive fish into shallow water.

The species exhibits complex migratory patterns, often moving south from regions where rivers and lakes freeze in winter. While they are generally not threatened, they occasionally face conflict with human interests, particularly game-fishing, due to their appetite for salmon and trout. In the United Kingdom, the goosander first bred in 1871 and has since expanded its range across northern England, Wales, and into the south-west. Whether floating gracefully down a river or resting on a rock with wings half-open to the sun, the common merganser remains a highly adaptable and resilient inhabitant of diverse aquatic landscapes.

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