You Do Need power plug adapter while traveling from Saint Barthélemy 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 Saint Barthélemy are C and E. This is how they look like.

Saint Barthélemy

In Saint Barthélemy, outlets of type C and E are in use.

Type C

Type E

Niger

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

Type C

Type D

Type E

Type F