Bizarre Bluebird Behavior

[John Barth -he, him-]

At least four times in the last two days, a male Eastern Bluebird nesting in our backyard has grasped the window sill and repeatedly tapped on our window. Once was on the bay window at the front of the house, but the other three times were all in the same corner of one of our kitchen windows. We don't have any reflective treatment on the windows. We have had previous occasions of birds flying into the windows and stunning themselves, but have never witnessed this repeated tapping behavior. Has anybody else seen this happen with Bluebirds or others?

John Barth

Sugar Hill