Saw 2 hawks in a rural farming region near Wolfville, Nova Scotia, Canada, Jan29,2012. Looked fairly large, not as big as an eagle though.
There's only a few hawks and falcons in Nova Scotia but I really don't have a clue which it is. The photos show the underside white and grey/blueish color patterns well and a dark grey head but they all seem to have the same underwing pattern. White underside for tail too.
I think there is maybe 4 large hawks/falcons that reside in Nova Scotia
Rough-legged Hawk, Peregrine Falcon grey head, Gyrfalcon, Northern Goshawk