Australian Shelduck
Tadorna tadornoides
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.
ID text from Wikipedia, CC BY-SA 4.0
Common Shelduck
Tadorna tadorna
The common shelduck resembles a small short-necked goose in size and shape. It is 55–65 cm long and with a wingspan of 100–120 cm, with a reddish-pink bill, pink feet, a white body with chestnut patches and a black belly, and a dark green head and neck. The wing coverts are white, the primary remiges black, and the secondaries black with a strong green iridescent reflection in good light (only showing in flight). The outer tertial feather is orange-brown, with the inner tertials white. The underwings are white, except for the flight feathers, which are black.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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