The Australian shelduck (Tadorna tadornoides), also known as the chestnut-breasted shelduck or mountain duck, is a shelduck, a group of large goose-like ducks part of the bird family Anatidae. The genus name Tadorna comes from Celtic roots and means "pied waterfowl". They have a striking chestnut-coloured breast and black body. They are protected under the National Parks and Wildlife Act 1974.
The males are mostly dark, with a chestnut breast. They have white neck collars and dark green heads. The females are similar, but they have white around the eyes and are smaller. Both males and females have chestnut and black wings with a green speculum, and show some white on their wings during flight.
The downy young are white with a brown crown and brown stripes from crown to tail. Juvenile males are duller than the adults and also lack a white collar, while juvenile females have a lot more white on their excluding their crown.
The vocal calls of the male are a deep honk similar to a goose, while the female's call is a high pitched and penetrating "zeek, zeek".