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Position in the tree Birds Aves › Birds with a flexible palate Neognathae › Fowl Galloanserae
Red-breasted Merganser | Mergus serrator
Middelste zaagbek | Serreta mediana
The Red-breasted Merganser is a slender merganser that breeds around the North Pole and in winter lives mainly on salt water. It is the merganser most often seen in the guide area: along the coasts of northern Mexico a fairly common winter visitor, mostly females and young birds.
Voice
Usually silent in winter. The female gives a hoarse, rasping krrr-krrr; in display the male a soft, cat-like yee-ow.
Recording: Stanislas Wroza — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
51–64 cm. Long and slender, with a thin, red, serrated bill with a hooked tip and a double, ragged crest on the rear of the head. The male has a dark green head, a white collar, a rufous streaked breast with black and white patches on the side, a black back, grey flanks and a red eye. The female and juveniles are grey with a rufous head that merges without a sharp border into the pale throat and neck. In flight elongated, with a white wing patch divided by one or two black bars.
Confusion species
In the female Common Merganser Mergus merganser the border between the rufous head and the white throat and breast is sharp, with a distinct white chin patch; the bill is thicker at the base and the crest smoother. The female Hooded Merganser Lophodytes cucullatus is smaller and browner, with a broad, fan-shaped crest and a dark upper mandible. Grebes and cormorants, which also sit low in the water and dive, lack a red bill.
Habitat
Shallow coastal water, bays, lagoons and estuaries, also over seagrass beds; rarely on lakes and reservoirs inland. It dives for small fish, often in small groups that herd a shoal together.
Where the bird is most at home, classified by the vegetation units of Mexico and Central America.
Range and movements
Winters along the Pacific coast and in the Gulf of California, in Baja California, Baja California Sur, Sonora and Sinaloa, and along the Gulf coast from Tamaulipas to the Yucatán Peninsula, in Yucatán and northern Quintana Roo; in small numbers also inland in Nuevo León, Coahuila and Chihuahua. Rare further south. Breeds in northern North America, Greenland and northern Eurasia.
- Winter visitor (c. Oct–Mar)
- dark = core range, pale = thinly spread
How and when to look
Lagoons and harbours along the Gulf of California and the north coast of Yucatán, where small groups of females and young birds dive close inshore; the thin red bill and the ragged crest are visible even at a distance.
Conservation status
Not threatened globally. The North American population is roughly stable. In the guide area a fairly common winter visitor along the northern coasts.
Scientific name
Mergus serrator | Linnaeus, 1758
Linnaeus described the species in 1758 and placed it straight away in the genus where it still stands. He introduced the genus Mergus in that same work. Mergus is the Latin word for an unidentified waterbird mentioned by Pliny the Elder and other authors; some have taken it to be a cormorant or Scopoli's shearwater. serrator is Latin for 'sawyer', from serra 'saw', after the saw-like teeth along the bill with which the bird grips slippery fish. The specimen the first description was based on came from Sweden.