Busy Bluebirds

Recently, I have noticed swarms of Eastern Bluebirds flitting about making as much noise as bluebirds can make in a group of about 15-24. I have three houses up on my property and one has been occupied the last couple of years by the same pair. Both summers they had three-four broods. Now I am wondering, since I have multiplied the population here if they are staying together in a flock or if this is normal for them. They usually seem dispersed throughout the neighborhood, but now it seems as if they are traveling around and feeding together. If anyone knows anything about this phenomenon, please let me know what is happening here! It's wonderful, but weird.