Common Merganser

The Common Merganser, known as the Goosander in Eurasian regions, is a striking large sea duck. Males are resplendent with a black head sporting an iridescent green sheen, a white body with a salmon-pink tinge, a grey rump and tail, and wings that are white on the inner half and black on the outer. Females and non-breeding males are more subdued in color, with grey bodies and reddish-brown heads.

Identification Tips

Adult males in breeding plumage are unmistakable with their contrasting colors and glossy heads. Females and eclipse males are predominantly grey with a distinctive reddish-brown head and a white chin. Juveniles resemble females but have a black-edged white stripe between the eye and bill. The species is characterized by a crest of longer head feathers, which typically lie smoothly rounded behind the head.

Habitat

These birds favor rivers and lakes surrounded by forested areas, where they can be found swimming or resting on rocks or ice edges.

Distribution

The Common Merganser breeds across northern Europe, Asia, and North America. It has three subspecies, each with slight variations in size and bill shape, distributed in northern Europe and Asiatic Russia, Central Asian mountains, and North America.

Behaviour

Common Mergansers are adept swimmers and divers, often seen in groups herding fish into shallow waters for easy capture. They are partial migrants, moving away from frozen waters in winter. Males may undergo a moult migration, leaving breeding areas to spend the summer elsewhere.

Song & Calls

Their typical call is a low, harsh croak, but during breeding season, males and young may emit a soft, plaintive whistle.

Breeding

Nesting usually occurs in tree cavities or large nest boxes, with the female laying 6-17 eggs. Ducklings are led to water soon after hatching and are independent after about 60-70 days.

Similar Species

While the adult male is quite distinctive, females and non-breeding males may be confused with other grey-bodied ducks, but the head color and bill shape are key differentiators.

Diet and Feeding

Primarily piscivorous, these ducks have serrated bills to grip slippery fish. They also consume a variety of other aquatic organisms, including molluscs, crustaceans, and insect larvae.

Conservation status

The Common Merganser is currently not threatened, though it faces illegal persecution in some regions. Its range has expanded southward in western Europe since the mid-19th century.