One of the 2 mergansers on WAnimals
Birds · Anseriformes · Anatidae
Red-breasted Merganser
Mergus serrator
The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary
A medium-sized sea duck with a very long, narrow red bill serrated along the edges, and a characteristic crest of ruffled feathers that it shows in every plumage and at every age. The breeding male has a black head with a greenish sheen, a white collar and a mottled brown breast.
Weight
908 g – 1.1 kg
Size
52 cm – 58 cm
Lifespan
9 years
Diet
Piscivore
Feeds mainly on fish.
Activity
Diurnal
Active mainly during the day.
Social structure
In pairs
Usually lives in pairs, sometimes for life.
Sighting difficulty
Easy
Estimated population
An average of about 300 wintering birds on the Iberian coasts, concentrated in Santoña, the Ría de Arousa, the Odiel marshes, the Mar Menor and the Ebro delta
Fun facts
- Its bill carries backward-pointing horny barbs that work like a saw and stop fish escaping once caught: hence the specific name serrator, "sawyer".
- It is a powerful flier that reaches 129 km/h in level flight.
- The Mar Menor has at times held between 20% and 40% of the Iberian wintering population and 5% of the world total.
Life cycle & biology
- Skeleton type
- Vertebrate - internal bony skeleton (bird)
- Habitat & environment
- Coastal waters: rías, estuaries, bays and coastal lagoons. In Spain it appears above all on the Atlantic and Cantabrian coasts, as well as the Mar Menor, the Odiel marshes and the Ebro Delta
- Birth weight
- Precocial: born covered in down and leaves the nest within a few hours
- Size at birth
- Precocial: born covered in down and leaves the nest within a few hours
- Sexual maturity
- 2 years
- Gestation / incubation
- 32 days
- Litter / clutch size
- 10
Sources consulted: SEO/BirdLife (ficha y III Atlas de las aves en época de reproducción en España); IUCN Red List; Asturnatura; Romay Cousido y Justo Álvarez 2022, III Atlas; Vera y Giménez en SEO/BirdLife 2012; Craik, Pearce y Titman 2020, Birds of the World; De Juana y García 2015
Where to find it
See its range on the interactive mapBest time: From November to mid-April, peaking in midwinter
Where to watch it
Parques y spots de buceo donde se ha documentado esta especie — se muestran 10 de 21 documentados.
Related species
Other species in the catalogue with the most in common with Red-breasted Merganser — same habitat, park, country, tags or family.
Whooper Swan
Cygnus cygnus
Goosander
Mergus merganser
Common Shelduck
Tadorna tadorna
Least ConcernMute Swan
Cygnus olor
Brent Goose
Branta bernicla
Common Goldeneye
Bucephala clangula
Keep exploring
Based on what we already know about red-breasted merganser.
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