I think I finally have a pair of bluebirds nesting in my nearby bird box with a pair of swallows nesting in the other box near it. I had this wonderful luck for several years running and then the house sparrows moved in and chased the bluebirds away. This year I stuffed the entrance hole of the box that the sparrow favored. After several days he took off and a pair of bluebirds moved in! The swallows were already building their nest in the adjacent box. Hopefully I will see eggs in the bluebird box soon!
This isn't a great photo especially since the bluebird flew off right when I snapped it, but if you look closely you can see the swallow on the box to the right. This photo was shot from my front porch, so you can see the boxes are quite close, which is why I am anxious to have my favorite song birds nearby.