Dan,
You are probably a Canadian citizen, if your mother never renounced Canadian citizenship before your birth. Apply for a citizenship certificate and you will know exactly. See the link below:
http://www.cic.gc.ca/english/information/applications/guides/CIT0001ETOC.asp#CIT0001E4
If you were born outside Canada to a Canadian parent on or after January 1, 1947, then send the following supporting documents:
A birth certificate which lists your parents (issued by the responsible government authority in the country where you were born);
Proof that one or both of your natural parents was, at the time of your birth, a Canadian citizen (i.e. your parent's provincial or territorial birth certificate, naturalization certificate, Canadian citizenship certificate or registration of birth abroad certificate);
Two (2) pieces of personal identification, such as a passport, a driver's licence and a health insurance card, one of which must have your photo on it;
If neither of your parents were born or naturalized in Canada before your birth, and either of your parents, or any grandparents, was employed outside Canada in or with the Canadian Armed Forces, the federal public administration or the public service of a province or territory, other than as a locally engaged person, please submit evidence of your parents or grandparents' employment (see section on Crown servants in this guide for further instructions and acceptable proof of your parent/grandparent's employment as a Crown servant);
Other documents, such as a marriage certificate/divorce certificate and/or a legal name change certificate (if applicable)
