Adding to the pair of Ravens sighted at Downsview Park and the pair building a nest by the spit, a pair have returned to the Bell transmission tower by Eglinton & Pharmacy. I've caught some glimpses over the past few weeks, but yesterday was the first time I got a good enough view to be 100% sure they weren't crows. I'm guessing they are either the same pair or offspring of the pair that nested there last year.
The nest is a bit hard to see because it's really high: about halfway up on a catwalk adjacent to the west post where there is an antenna sticking out the side.
So it appears there are at least 3 pairs of Ravens in Toronto this year, 2 of which have, or are building nests. I don't know if that's completely unprecedented if you go far enough back in history, but it certainly hasn't happened in a very long time.
BB