Stats NZ reports:
Net migration from Australia continued to rise, with a net gain of 1,900 migrants. This is the highest annual net gain of migrants from Australia in about 25 years (since the August 1991 year) and the sixth consecutive month to show an annual net gain. One in five migrants arriving in New Zealand in the March 2016 year came from Australia, and most were New Zealand citizens returning.
This graph shows the trend:
Departures to Australia are at an all time low and arrivals from Australia at an all time high.