Breed in much of temperate and northern Europe into Asia; and migrate south to winter in southern and west of Europe. In the British Isles, they breed in eastern England and lowland Scotland, and to a lesser extent in Northern Ireland. Many of them overwinter in Great Britain, after leaving their summer territories in Russia and Scandinavia, where they breed in marshes and lakes with a meter or more water depth.
The adult male has a long dark bill with a grey band, a red head and neck, a black breast, red eyes and a grey back.
The adult female has a brown head and body and a narrower grey bill band. The triangular head shape is distinctive.