Robin sighting in Toronto, a sign of spring?

yes and no

#Robins travel in the winter from the north to southern states and warmer climates but some Robins stay in the north, depending on food availability, and those who traveled to the south might return back to north with spring.

Robins have a wide wintering range because of their downy feathers that help them live through snow. Both food availability and temperature can affect their whereabouts, and migration in the winter and the spring.