Maybe a Barred Owl? Not much smaller than a Great Horned-Owl and superficially similar to Great Gray Owl. The swampy habitat fits well for this species also. -O-

Thanks for the links. The Great grey is my favorite owl and I can never see enough pictures of them.

Very beautiful photo's of such a magnificent bird.. Claire

That is a Great Gray Owl (Strix nebulosa). That's a great find for a backyard bird! It does look a bit like a Barred Owl but it is too "big-headed" and the white under the face makes it Great Gray. I would love to see one of those in my backyard....or anywhere for that matter!