I am popping this back up to update and ask a couple questions.
We've never seen this particular Great Horned Owl, but we continue hearing it off and on. In the shortest winter days, we heard it (strangely) around 4:30 pm and sometimes after 7am. It was always coming from northeast of our place. Maybe there is a nest along the creek. ?? In the overnight hours sometimes it does sound like it is in the yard, or very close.
Last Friday, our 5 year old found this pellet in the yard. I messed with it trying to determine what animal was eaten. It looks to be a small rodent- mouse or vole. At was about the size of a quarter before I messed with it.

When I asked him exactly where he found it. He could only say, "The ground". Sigh... An older child was outside when it was found and gave me a general idea. We looked for more pellets, but couldn't find any.
Do Great Horned Owls ever eat prey as small as mice? I know raptors cough up pellets, so it could be one of them. The other raptors we have seen within the last month are the Northern Harrier, American Kestrel, Red-tailed Hawk, Cooper's Hawk. We've never seen any of the smaller owls around here. Not to say they aren't. I know this is a long shot, but there's no way to determine what hacked this up, is there?
Life list (non ABA)- 204 Latest: American Golden-plover Coolest: Audubon's Warbler
2013 Year list- 159 Latest: American Golden-plover
Yard list- 107 Latest: Great Egret Coolest: Lesser Yellowlegs (This bird was terribly lost during our May snow, we are near no shore for this shorebird)