I too bet it was a great horned owl! Almost every night, I have 2 GHO that "visit" me. We "who,who" back and forth, and then they are off to find dinner (that part I want NO part of!!) Have you ever watched an owl when they are "who, who...ing?" They lean forward and puff up their feathers, it is very cool!
I had not been out there for 3 or 4 nights, and my husband looked out, and one of the owls was standing on our steel bldg looking at us thru our back patio doors!! I am being stalked by an owl, LOL!!! Here is a recent photo of one of them:
