You Do Need power plug adapter while traveling from Mauritania to Kiribati.

Here is Why You Need An Adapter

The outlet and plug type used in Kiribati is I and in Mauritania is C. This is how they look like.

Mauritania

In Mauritania, outlets of type C are in use.

Type C

Kiribati

In Kiribati, outlets of type I are in use.

Type I