That would be a Musk duck
Scientific name: Biziura lobata
Family: Anatidae
Description
The male Musk Duck is the largest of Australia's ducks and has a powerful build. Musk Ducks get their name from the strong musk odour produced from a gland on the rump. The female is smaller than the male. Both male and female Musk Ducks are sooty-brown in plumage, with paler brown barring on the body and fine spots of the head. They are paler below, becoming whiter towards the abdomen. The male is decorated with a large bulbous lobe of skin hanging under his bill. This sac increases in size at the start of the breeding season. The female also has a much-reduced lobe on the underside of its bill, only visible at a short distance. The bill is dark grey in both sexes and the eye dark brown. The tail is a collection of long, stiff feathers, which can be held in a fan-shape. Young Musk Ducks are similar to the adult female, but are paler, with a dull yellow tip on bill, and no lobe