Tawahi was suffering from ''egg-binding'', which meant she would be unable to lay the egg.
''Even with healthy kiwis there's a risk they won't survive the anaesthetic or surgery.
''She was a really sick kiwi - she already had aspiration pneumonia, she'd inhaled some of her stomach contents because she was pushing, and that makes it a massive anaesthetic risk.''
Tawahi arrived at the vets' at about 3.30pm and Dr Fitzpatrick, vet nurse Georgia Affleck and park manager Paul Kavanagh were still there at 1.30am.
''It was a real team effort. Her heart stopped twice during recovery but Georgia was able to administer emergency drugs - she was brilliant.
Any time that we're operating or involved with a native bird like a kiwi, which is so important, it's kind of stressful.''
While the egg was not viable, Tawahi survived, although she still has some way to go to a full recovery from the Caesarean.
''She is over the riskiest part, [but] she is still not completely out of the woods,'' Mr Kavanagh said.
He praised the VetEnt team, particularly Dr Fitzpatrick.
''She goes above and beyond to help save animals, especially when it comes to our native wildlife.''
A Kiwi egg is one of the largest in relation to body size of any bird, about one sixth of the female's body weight.
Tawahi's unviable egg weighed about 400g, the equivalent of giving birth to a 15.9kg (35lb) baby.
