I found a singing Canada warbler yesterday (June 17) on private property in the Sheldon Creek Valley, Mono Township, Dufferin County. Ovenbird, black and white warbler, black-throated green warbler, winter wren, and ruffed grouse in same area.
They seem to be quite uncommon breeders, but present in very small numbers in larger forested areas (mixed forest, not pure deciduous stands) of this region.