Chestnut Teal
Anas castanea
The chestnut teal is darker and a slightly bigger bird than the grey teal. The male has a distinctive green coloured head and mottled brown body. The female has a brown head and mottled brown body. The female is almost identical in appearance to the grey teal. The female chestnut teal has a loud penetrating "laughing" quack repeated rapidly nine times or more.
ID text from Wikipedia, CC BY-SA 4.0
Pacific Black Duck
Anas superciliosa
This sociable duck is found in a variety of wetland habitats, and its nesting habits are much like those of the mallard, which is encroaching on its range in New Zealand. It feeds by upending, like other Anas ducks. It has a dark body, and a paler head with a dark crown and facial stripes. In flight, it shows a green speculum and pale underwing. All plumages are similar. The size range is 54–61 cm (21–24 in); males tend to be larger than females, and some island forms are smaller and darker than the main populations.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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