Hi Aaron
In theory I think you should be able to find them, but I am having the same problems - found them in the first place I looked in Whangarei, but have tried about 10 different likely spots around Wellington and haven't seen one!
I have read that the further south you go the lower the maximum altitude they can be found at, implying that they dont like the cold so much, which might impact their numbers in general as you go down the country.
lots of knowledgable people on here though, so hopefuly someone can help you out