I went to the front door and looked out the glass side lights and didn't see anything. But the noise was definitely coming from the other side of the door.
I turned the lock, thinking that whatever was out there would be frightened by the sound. But it wasn't. I opened the door and this young mourning dove nearly fell into the living room.
It had been pecking at its reflection in the brass kick plate.
It righted itself after the near-spill into the living room and faced down the enemy once more.
It got breast to breast with the rival bird and continued to peck away.
After a few more minutes of fruitless scaring-the-other-bird-away maneuvers, it decided to move on.
See you around the neighborhood, little bird!