Could be a hawk of some sort ... I've been watching a hawk nest (near Guelph) over the last week, which doesn't look unlike the one in your picture, but I have been unable to formally identify the occupier - all I see is the tail feathers, and occasionally a head will pop up for a second or two. Since I can see the tail I'm pretty sure it's not a red-tailed. Just for the record a squirrel home is usually referred to as a dray (sometimes it pays to watch Jeopardy
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