What's that noise?

We were minding our own business when the knocking sound stated. I sounded just like someone was up on the roof with a small hammer tapping away. This wasn't the first time it's happened. Sometimes the bluejays will do it. It kept up for a bit. So I went outside to see if I could see the culprit. There he was testing to see if he could give us another leak. I went back in to grab the Nikon. No sooner than I stepped outside again he flew to the oak in front of the house.

The light was all the better for it.