Birdsong field guide
Scaly-sided Merganser
Mergus squamatus
A rare and striking sea duck characterized by its distinctively patterned 'scaly' flanks and long, wispy crest. It is an endangered species primarily found in East Asia's pristine river systems.
What it sounds like
Usually silent; males occasionally emit low, gravelly croaks or rhythmic grunting sounds during display.
Field notes
- It is globally endangered with a total population estimated at fewer than 5,000 individuals.
- Unlike most waterfowl, it nests in natural tree cavities or old woodpecker holes in large, ancient trees.
- The 'scaly' appearance is produced by dark, crescent-shaped markings on the white flanks of the adult male.
- It serves as a key indicator species for the health of primary forests and unpolluted freshwater ecosystems.
- Both sexes feature a long, shaggy double-crest, though the male's is typically more prominent.
Habitat
Old-growth forests adjacent to clear, fast-flowing rivers during breeding; large rivers and coastal wetlands during winter.
Range
Breeds in Far East Russia, Northeast China, and North Korea; winters in Southern China, South Korea, and Japan.
Similar & commonly confused birds
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