Previous Stats NZ definition of a write-in for 'kiwi' or 'New Zealander' as an ethnicity: 'Doesn't know what 'ethnicity' means. Probably white.' New definition: 'Doesn't like to think of themselves as white, so we'll just go along with it because we're sick of this stupid argument.'
NB: Recipe to come next week.
There are a few ornery Chinese and Maori out there - just a few - who won't fill out their ethnicity in the Census or in any other forms. They're 'just New Zealanders', you know, 'kiwi.' Or as some might uncharitably put it, Bananas and Bounty Bars. But we all know the rest of those Census 'Kiwis' and 'New Zealanders' are Pakeha. You meet enough of them, the ones who go on and on about not being Pakeha. Ethnic identity is self-defined and there's nothing anyone can or really should do about that. Ethnic heritage however, which is what the Census is actually trying to measure (ie where your ancestors came from and possibly when they came), is a priori - you can't just make it up. What this change means is that the Census is now going to be measuring how many people are trying to make it up.
Sidestepping most of that argument though - you Pakeha/Kiwi/New Zealanders can have it amongst yourselves - here's how my Singaporean/Malaysian Chinese corner of the country uses the word 'kiwi'.
Guess what - it means White.
'Oooh, Corrina's engaged you know or not!'
'Meet from Church that boyfriend one?'
'Yeees, gone out a long time already.'
'Chinese is it?'
'No, Kiwi boy.'
'Oh, babies will be very cute!'
[Frantic giggling ensues. Aunty Anne Bong then tells the story of how her grandfather James Bong acquired his name from a confused immigration official]
Okay, those Singaporean-Malaysianisms were somewhat exaggerated, but it's always fun to write in Singlish even if I don't speak it.
For us, as a noun referring to a person, as used by my parents' generation and to a large extent by my own, 'kiwi' means white, and a specific kind of white at that. It means Pakeha. Corrina's fiance would have been referred to as both 'kiwi boy' and 'local boy.' If he had been German or something we would have called him German. So yes, it seems feasible that 'kiwi' is an ethnicity, and Stats NZ have sensibly used it as a placeholder for 'New Zealand-European' for yonks.
In my family-friends' discursive context, 'Kiwi' can be applied to non-Pakeha in a way that straddles that difficult categorical divide between a cultural trait and an ethnic one. But for the most part, we consider being 'Kiwi' to be a cultural, not an ethnic identity because we, like, already have our own ethnicity. The thing with being Singaporean/Malaysian Chinese is that your ethnic identity already has that extra overlay of a nationality-seguing into an ethnicity, so adding another one would just be an enormous hassle.
The clearest case of the use of kiwi as an adjective, would be my parents saying, after over thirty years here, that they are "quite Kiwi." It's like saying we've been "Frenchified", yeah? Ultimately, it doesn't really matter , because when it comes down to a choice on a Census form that obviously leans towards the less postmodern purpose of measuring ethnic ancestry, ticking no boxes and writing in 'Kiwi' would be, for a non-Pakeha person, a denial of their actual ethnic heritage. And boy would they get it from their parents.
I think that for a Pakeha, the same choice is a denial of the Anglo-Celtic-Euro-settler part of what comprises their kiwi-Pakeha 'ethnicity'. It also seems a belief that 'Kiwi' is a universal ethnicity, and that anyone can be a 'Kiwi' and nothing else, just like them, standing rather defiantly and nicely against the Australian example where 'Aussie' or 'Ocker' means White. Well, it's a nice sentiment and works if you think of 'Kiwi' as a shared culture - but not an ethnicity. We non-whites can't just be Kiwis and nothing else. And a lot of us don't want to.
Meanwhile, claiming 'New Zealander' is an ethnicity rather than a citizenship-status, well that's just bizarre. I give up.
For reference, here's the good old Ethnicity Definition in Michael E. Brown's 'Ethnic Conflict and International Security', p 4-5.
First, the group must have a name for itself. This is not trivial; a lack of a name reflects an insufficiently developed collective identity. Second, the people in the group must believe in a common ancestry [my emphasis]... Third, the members of the group must share historical memories... Fourth, the group must have a shared culture, generally based on a combination of language, religion, laws, customs, [etc]. Fifth, the group must feel attachment to a specific piece of territory, which it may or may not actually inhabit. Sixth and last, the people in the group have to think of themselves as a group in order to constitute an ethnic community; that is,they must have a sense of their common ethnicity. The group must be self-aware."