Of course my presence could well have distracted the NNZD but I don’t think she could defend her nest. The whole time I was observing her she was never more than a few meters from her nest. A passing cow would have been a much bigger and very common distraction for her. The Pukeko was moving with two others who stayed nearby but did not seem interested, there were no observable Pukeko chicks (or paternal behaviour from the Pukeko). The Pukeko definitely seemed to be consuming the egg for food not destroying it for territorial reasons.
Egg predation by Pukeko might explain other nest losses I have had this season.