Claudia, that's probably why you don't see the bluebirds this year. We also have a huge owl around here but they go more for the mice, etc. Last year an eagle landed in our front yard and hung around for a couple of days. They are so common now that it isn't as exciting to see one as it was a few years ago.
Melanie, when we travel out west, we always see lots of Hawks on fence posts and those big round bales. They are watching for rodents and they are really quick for such a big bird.