Red-breasted Merganser
Mergus serrator
Tap image to enlarge · Wikimedia Commons
Overview
The Red-breasted Merganser is a fish-eating diving duck with a shaggy crest and a serrated bill for gripping slippery fish — the serrations give the 'sawbill' ducks their collective name. The drake has a bottle-green head, red-orange bill and, in spring, a chestnut-streaked breast. They pursue fish underwater at speed. The Alt Estuary channels are a reliable spot in winter. When a group of Mergansers herds fish together in a tidal channel, the co-operative fishing behaviour is worth watching.
At a Glance
| Order | Anseriformes |
| Family | Anatidae |
| Habitat | Estuary · Coastal sea · Tidal channel |
| Diet | Fish — chases fish underwater with serrated bill |
| UK population | Around 3,000 breeding pairs; winter population around 8,000 |
| Sefton Coast | Regular winter visitor to the Alt Estuary and adjacent coastal waters; small numbers |
| Conservation | UK Amber List |
Where to See It
Alt Estuary and offshore from Ainsdale and Formby. Occasionally the Ribble channels.
Identification
Long, low waterbird. Drake: dark green shaggy-crested head, red serrated bill, white collar, chestnut breast. Duck: brown head with white chin, same red bill. Often swims low with bill submerged scanning for fish.
Viewing & Photography Tips
Check the Alt Estuary channels at low tide in winter. Mergansers fish actively and are easier to find when there's tidal movement concentrating fish.
Conservation Status
UK Amber List
This species is on the UK Amber List for Birds (BoCC5), indicating moderate concern. Population monitoring and habitat management remain important for its continued recovery.
Frequently Asked Questions
What is the difference between a Red-breasted Merganser and a Goosander?
Both are sawbill ducks with serrated bills, but they differ in habitat preference and appearance. Goosander is larger with a bulkier head (no crest on the duck, though males have a green head). Merganser has a distinctive shaggy, double-pointed crest on both sexes. Mergansers prefer saltwater and estuaries; Goosanders favour rivers and freshwater. On the Sefton Coast, Mergansers are the coastal bird and Goosanders more likely inland.
Related Species
Plan your visit to the Sefton Coast
Marshside RSPB, Formby pinewoods, Ainsdale NNR — practical guides to getting there, what to bring, and the best spots for each season.