Family Ducks, Geese, Swans (Anatidae)

Least Concern

Red-breasted Merganser (Mergus serrator)


French: Harle huppé German: Mittelsäger Spanish: Serreta mediana

Mergus Serrator


, 1758,



Greenland population previously treated as a geographical race, schioleri, but differences slight and deemed to fall within range of individual variation of the species as a whole#R. Monotypic.


Breeds in most of N North America S to Great Lakes; Greenland, Iceland and most of N Eurasia S to Britain, parts of E Europe, NE China and N Japan. In winter expands range S to both coasts of North America, C Europe and Mediterranean Basin, Black and Caspian Seas, S coast of Iran and Pakistan, and coasts of E China, Korea and Japan.

Descriptive notes

52–58 cm; male 947–1350 g, female 900–1100 g; wingspan 67–86 cm. Large, long- and relatively slim-bodied sawbill, with long, narrow, serrated, hook-... read more


Male utters complex, wheezy, cat-like “yeow-yeow”, single-noted “yeow” or loud, rough-sounding... read more


Breeds on rather deep lakes and rivers (including their estuaries) with only moderate currents,... read more

Food and feeding

Small, shoaling, freshwater or marine fish; also aquatic invertebrates (especially crustaceans, but also worms, insects and amphibians) and... read more


Starts Apr/Jun, depending on latitude, with nesting starting between late May and mid Jul in New Brunswick, first eggs in Britain in late... read more


Partially migratory: in W Palearctic males first to depart breeding areas (from early Jun) to moult... read more

Status and conservation

Not globally threatened (Least Concern). No total estimates of population size available, but North American spring population calculated at c. 237,000 birds in mid 1970s and... read more

Recommended citation

Carboneras, C. & Kirwan, G.M. (2020). Red-breasted Merganser (Mergus serrator). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 28 January 2020).