your opinion of animals appears to be that if you can't feed it another live animal then it is worthless. To say that NZ's fauna is dull and uninteresting is to display ignorance on an epic level. Everywhere on Earth has animals that are amazing, and NZ happens to have a higher than usual ratio due to the conjunction of various factors such as being an island, being isolated from other land-masses for 80 million years, the lack of mammalian influences, etc etc. To live in NZ is to be the envy of many zoologists or naturalists from other parts of the world. Just off the top of my head I can think of many fantastic NZ species which could by no stretch of the imagination be called uninteresting, such as live-bearing geckos, bioluminescent freshwater limpets, a predatory alpine parrot, the world's largest springtail (1cm long!), alpine flies with "solar-powered" wings, giant crickets bigger than mice. Going back just a millenium, before the arrival of humans to the islands, there was the world's largest gecko, largest eagle, tallest bird and others. It can't be doubted that a scarlet macaw is more brightly-coloured than a kakapo but the latter is the world's only flightless parrot, the heaviest parrot, the only fully-nocturnal parrot, the only parrot that has a lek system for breeding (as well as being the only flightless lek bird). To suggest that the parrots here are boring because they aren't brightly-coloured is to show a shallowness worthy of a supermodel.
And as for the survival of snakes, please don't comment on things of which you are profoundly lacking in knowledge. There are literally dozens of species of snake that would survive perfectly well in NZ's climate. The latitude of snake distribution reaches to 69 degrees North in Scandanavia and 45 degrees South in Argentina. Just in Australia there are several species that could potentially establish populations in parts of NZ.
I'm not really sure what you think you mean by "perhaps spiders and arachnids would survive in nz wether, but even that, is unlikely".