We put a nesting box in our backyard for the Bluebirds but the Tree Swallow took it over and built their nest in it. We watched them all summer as they laid their eggs and then disappeared into the nesting box to incubate the eggs. Soon we began to hear little chirps inside the box and we knew they had baby birds. When the adults brought bugs there was a lot of squawking from the little ones inside. As time went on, we began to see the babies poke their head out of the box and knew it would not be long before they fledged. Every day we watched, hoping we would get to see them take their first flight. One morning we sat at the breakfast table thinking it had to be any day now that they would fledge. We got busy doing our yard work and when we sat down for lunch we noticed the adults were not taking bugs into the box any more. We missed the fledging. Two days later we noticed the adult pair doing what we thought was a mating dance on top of the nesting box but they never built another nest. We have since decided they were arguing over how to raise the juveniles.