I live in Toronto and just had a visitor to my yard that I have never seen before. It's small bird (a bit smaller than a sparrow) and appears to be olive/green on top with yellow tones on the breast/belly, has a white (maybe tan) eye ring and long, narrow bill. At first I thought it was a female/juvenile Goldfinch but when I zoomed in with my camera I didn't see the familiar wing markings of a Goldfinch and the bill looked different. Also the body shape of this bird looks different from a Goldfinch. This bird is roundish.
I'm thinking a female Connecticut Warbler. My area is along their migration path.
I have attached a picture. My apologies for the quality. This bird kept to the shadows and at the far reaches of my zoom lens.