Upvote:2
When you travel on your Canadian passport, you won't be using your ESTA authorization. You won't be using the visa waiver program. It's therefore not necessary to keep your ESTA registration up to date (if that's even possible).
Upvote:4
The ESTA guidelines say:
Each approved ESTA application generally is valid for two years or until the applicant’s passport expires, whichever comes first. A new travel authorization is required if: (1) the traveler is issued a new passport; (2) the traveler changes his or her name; (3) the traveler changes his or her gender; (4) the traveler’s country of citizenship changes; or (5) the circumstances underlying the traveler’s previous responses to any of the ESTA application questions requiring a “yes” or “no” response have changed. The associated fee will be charged for each new application submitted.
My interpretation of this is that your ESTA is no longer valid. This is no issue for you, though, as Canadian citizens do not need an ESTA to travel to the USA.