I had a bit of a play around with mapping the voter return data from the 2016 Auckland local body elections (raw data available here). I looked at it two ways:
Maps addressing these two questions are below. Note that they don’t include Waiheke, mainly because it’s not part of the “Coastlines” shapefile I used to crop the board boundaries and I decided the effort of separately mapping the board area to the “islands” geographic shapefile wasn’t worth the effort given I have a day job (i.e. I am lazy). If you are wondering, turnout on Waiheke was very high (58.6%).