You Do Need power plug adapter while traveling from Canada to Pitcairn Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Pitcairn Islands is I and in Canada are A and B. This is how they look like.

Canada

In Canada, outlets of type A and B are in use.

Type A

Type B

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I