The breeding male has grey flanks and back, with a black rear end and a brilliant white speculum, obvious in flight or at rest. It has a pink breast, white belly, and a chestnut head with a yellowish crown stripe.
The females are light brown, with plumage much like a female Mallard. They can be distinguished from most ducks, apart from American Wigeon on shape. However, that species has a paler head and white axillaries on its underwing.
In non-breeding (eclipse) plumage, the drake looks more like the female.
It is a bird of open wetlands, such as wet grassland or marshes with some taller vegetation, and usually feeds by dabbling for plant food or grazing, which it does very readily. It nests on the ground, near water and under cover.
This is a noisy species. The male has a clear whistle, whereas the female has a low growl.