You Do Need power plug adapter while traveling from New Zealand to Niger.

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, E and F and in New Zealand is I. This is how they look like.

New Zealand

In New Zealand, outlets of type I are in use.

Type I

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F