Many robins over-winter in the GTA. They feed mostly off fruit during the winter.
We have a male who spends most of his day in our ornamental (small fruit) crab apple tree. He defends it rigourously off the other robins who sometimes flock through the neighbourhood. Strangely, he doesn't seem to care much if the house finches, waxwings or other birds stop by to eat a few crabapples. (One time I actually went and shooed a large flock of robins out of the tree for him, as he'd been trying for over 15 minutes to chase them off and was getting noticeably tired. He doesn't mind me or my family coming quite close.)
I believe they also eat sea buckthorn, buckthorn, rose hips etc.