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Red-breasted Merganser

A species of sea duck found off shore and in large harbours in winter 

Photograph by: 
Debby Saunders

When watching birds at sea one rarely gets a good view. The bird may be some way off, the light may be poor, the continual motion of the waves keeping the subject moving out of the field of vision of your binoculars and then, to cap it all, it dives beneath the surface! Despite that it is still often possible to make a positive identification through little signs.

Plumage colouration is only a part of the overall picture as I think this photograph shows. Obviously it is a 'duck' and it is on the sea so that narrows down the choice straight away and then, in profile, two key features are visible. The bird has a longish pointed bill, far from duck-like, and it looks like it needs a good feather brush to sort its head dress out! So with a distant view and no colours to go on this can still be named, a red-breasted merganser (Mergus serrator).

Whilst obviously nesting on land, in winter the red-breasted merganser prefers a life on the ocean wave! They are not a breeding species in Dorset but they do breed in Britain in western Scotland but the main population in spring and summer occur in the Arctic regions of Europe, Asia and America. We see them in the autumn and winter months where they spend their time on open water; usually the sea but also on some large lakes. They tend to stick together in small rafts but are fish eaters so regularly dive. As there are usually a group of them they are, however, usually quite visible with some being on the surface whilst others are below.

We do not see normally red-breasted merganser in Dorset in June, July or August. The autumn inward movement starts about week 39 in late September and numbers build during October. They are then present for the autumn and winter until April and whilst there are still some about in May by week 20 they are gone.

Seen off shore in sheltered open water in Studland Bay, Poole Bay, Weymouth Bay and the western reaches of the Solent off Mudeford and they are also quite at home in Poole Harbour and at points along the Fleet. There have been no inland lake reports since the Nature of Dorset database started in 2017,

Easily seen in Poole Harbour from many vantage points ticking red-breasted merganser on your Dorset list should not be a problem. 



Red-breasted Merganser: pass the comb please

Common Name Red-breasted Merganser
Scientific Name Mergus serrator
Species Group Birds Ducks
Status Local
Interest Level
  • 10 - October
  • 11 - November
  • 12 - December
  • 01 - January
  • 02 - February
  • 03 - March
  • 04 - April
Look for

Offshore flotillas of what appear black and white ducks

Identification Notes
  • Winter visitors to the harbours and seas around Dorset and very often seen in small groups, half a dozen or so
  • They may look black and white from a distance but the are green rather than black 
  • The feathers on their heads stand up and it looks like they need a good hair brush to sort them out!  
Primary Habitat
Preferred Environment
Look for
Additional Identification Notes
Similar Species

The records for this species have been organised into reports, charts, maps and photos. Click a pic below to see the detail:

Notebook Distribution Map Sites List Some Charts Some Photographs Recent Records Guidance Notes

To see related species click here: 

Birds Ducks