I think you will find those vacancies are before the interviews and offers and some are for midwifery only and nursing plus midwifery, there is no way they have all these vacancies at this time of the year.
I have, however, found the vacancies at this time of the year:
PMCV Computer Matching
and there is one or two at each of these hospitals, southern health having 22 for mental health graduate nurses.
It is possible that they may consider a non citizen or pr, the trouble is, it costs money for the sponsorship visa and the hospital has responsiblities when sponsoring. If they can fill it with a local or NZ citizens they, you would think, be first priority, but have a go, most of these are country hospitals and thats why they still have a vacancy.