Need help identifying in Hamilton, Ontario

by Danielle
(Hamilton, Ontario, Canada)

I see these two almost every day at work on my lunch break.

There are a few large old trees they seem to perch in and there is an empty field right behind that I see them hunting in.

Sorry, the picture is not great, my camera phone zoomed in as close as it will go, but one is facing me and the other facing away so it gives you a pretty good idea of the colouring of the back and underbody.

They are quite large.