I lost my birth certificate at YYZ last week (my passport is at the Brazilian consulate for a visa which I won't need after all). I realized I had dropped it when I got home at 10 p.m. I went back to YYZ in the morning and they had it at Customs! They actually have a very sophisticated system for registering found documents in case their owners claim them. Apparently they pick up about 60 a day.

So my recommendation is to check with them. I don't know if there is a number to call as I went in person.

Good luck!