Immigration, Refugees and Citizenship Canada released new ETA (electronic travel authorization) requirements in November that require all dual Canadian nationals travel with a valid Canadian passport. If their plane leaves within 10 days, they must apply for a special ETA to travel with their passport from a visa-exempt country.
The Globe and Mail reports that in the past 4 months since the new requirements, more than 8,400 Canadian citizens have needed emergency authorization to board a flight. For passengers only changing planes in Canada, the new rules require travellers with dual citizenship to have a Canadian passport. To learn more about the new ETA regulations and who they apply to, visit the Government of Canada's website.