Medium sized dabbling duck. Noticeably big and wide bill, giving the whole bird a front-heavy look. Male with dark green head, rusty brown flanks and belly. Vent and lower back black, flight feathers dark. Female brown with dark speckles, but with similar huge bill. Speculum green, lacking white rear edge. In flight the darker belly separates it from female mallards. Conspicuous forewing in flight; grey in females and light blue in males.

Male is characteristic and most often heard: A hoarse nasal knocking sound "took took", often staccato or disyllabic. Female similar to Mallard but flatter and more creaking.

Display-call male:

Wikipedia: map (se also Xeno-canto below)

Birdlife ecology

Observation.org Latest observations

Video IBC

Image search Flickr NB! May give other species

Sound search at Xeno-canto

Featherbase

CC-sound:Peter Boesman, Licence,Link.