Why new zealand have no snakes?

Coming from Australia, this is a big one. The short and sweet of it is that New Zealand broke away from the ancient supercontinent Gondwana about 80 million years ago. This happened long before snakes evolved and spread across the globe. So they simply never got there naturally.

Any that might have arrived over the millennia would have struggled. During the ice ages, the islands were far too cold for them. These days, their biosecurity is incredibly strict to make sure it stays that way. Honestly, the Kiwis are lucky buggers