The Paradise Shelduck in the first two photos is a female and in the last two photos a male. We can ID the duck in the first two photos as a female Paradise Shelduck by its goose-like appearance, white head and upper neck and a bright orange-chestnut body.
We can ID the duck in the last two photos as a male Paradise Shelduck by its goose-like appearance, glossy black head and neck, finely barred grey body and orange-chestnut tertials.
The Paradise Shelduck is endemic to New Zealand and is a new species to our Photographic Life List, which now stands at 742.