The Red-Breasted Merganser is a medium-sized saw-bill diving duck.
The adult has a spiky crest and long thin red bill with serrated edges. Adult males have a dark head with a green sheen, a white neck with a rusty breast, a black back and white under parts.
Adult females have a rusty head and a greyish body. Juveniles are like the female, but lack the white collar and have a smaller white wing patch.
Red-breasted Mergansers dive and swim underwater. They mainly eat small fish, but also aquatic insects, crustaceans and frogs.
Its breeding habitat is freshwater lakes and rivers across northern North America, Greenland, Europe and Asia. It nests on the ground in dense cover, often in loose colonies on islands or small islets and uses wooded shorelines along rivers or lakes.
In coastal areas, they are often observed at river mouths where, on islands, they breed in loose colonies and in association with terns and gulls.
It is migratory and many northern breeders winter in coastal waters further south. It winters in cool northern environments with abundant small fish.
The call of the female is a rasping prrak prrak, and the male gives a feeble hiccup-and-sneeze display call. It is one of the fastest birds in level flight, reaching speeds of 80 mph.