You answered as well my question on bird ID, and I am absolutely not sure. However, it was very like a large goldfinch, quite lemon yellow, with black on wings and black on head, heavy finch bill. It had a plain call, different from a goldfinch which I know well by sight and ear. I don't see a lot of orioles, but I usually see one each migration, and they are really orange, with a sharp black hood, and they sing more. It wasn't brownish with yellow like a female oriole, either. I actually immediately came to this site to check and see if anyone else is reporting them in Toronto, or even in my part of Toronto. It was so funny just the next day after seeing a rose-breasted grosbeak, which is pretty rare for me, and I thought maybe they migrate together in mixed flocks. I will leave my question open in my mind, and keep checking for other reports. And what else might it be???
Thanks for taking the time to answer!
