The theory that it might be young owls could be the reason. The summer I came out of my house to see my cat sitting about a foot from a screech owl that was sitting on the ground. I moved the cat and the owl tried to fly away and crash landed in the grass. I realized it was a fledgling and hadn't quite learned the mastery of the air yet. Later that night I heard something hit the sliding glass door of our balcony and got up to find the owl sitting on the balcony acting as if drunk (probably from banging its head!). It collected itself and finally flew off. Thinking that would be the end of it, the next night I heard another bang against the glass and there it was again! The second knock on the head must have finally gotten through to the owl that this was not a good idea and that was the last I saw of it. Screech owls pose no danger to humans, they are about 5" tall and rather cute, and mostly eat insects and mice, and the "screech" seems to be a misnomer as well because they frequently call at night but I have never heard anything approaching a "screech", more like a quite trill.
On the other hand we also have great horned owls here, and while none has ever been that close, I have seen them in our trees at dusk and once during the day when it was being mobbed by the other birds. This is a formidable looking owl and a friend head one carry off a young raccoon one night. Hopefully my cat is not dumb enough to get that close to one of these.
We also had an owl swoop in for a good look at my mother-in-law's chihuahua one night, he we not been standing there, who knows.....?
I did have a friend who worked for a cable company who was walking in the woods beneath some power-poles checking the cables. He heard a "whooshing" sound and the next thing he knew he came to lying on the ground with his head bleeding profusely. Seems he had gotten too close to a red-tailed hawk's nest and the bird nailed him in the back of the neck with both talons and knocked him out cold.
Edited by Sundew, 15 October 2012 - 12:11 PM.