Trying to identify an Ontario bird photographed in Spring in the Don Valley
Based on the location, timing and picture, this bird is a female Red-winged Blackbird (Agelaius phoeniceus)

In the spring in Ontario, it would be unlikely to have juveniles around, as breeding has just begun unless this photo was taken near the end of Spring. Male Red-winged Blackbirds would be in their dark black plumage with the yellow/red wing patch. Here is a photo of a pair with the male on the left and female on the right.



You can find more information about them here