It is a striking bird, with a reddish-pink bill, pink feet, a white body with chestnut patches and a black belly, and a dark green head and neck.

Sexes are similar, but the female is smaller, with some white facial markings, while the male is particularly crisply coloured in the breeding season, his bill bright red and bearing a prominent knob at the forehead.

Most populations migrate to subtropical areas in winter, but this species is largely resident in westernmost Europe, apart from movements to favoured moulting grounds, such as the Wadden Sea on the north German coast.

[11] Moulting flocks can be very large (100,000 on the Wadden Sea), since most pairs leave their partially grown young in a crèche with just one or two adults.

This species is mainly associated with lakes and rivers in open country, breeding in rabbit burrows, tree holes, haystacks or similar.