I have to share what I've learned about our crazy bluebirds. They are spending so much time at our nesting boxes. Honestly, you'd think it was May. Googled and found that the theories for this behavior are: they think it is spring because of the cool weather, they are house hunting for next year, they are practicing. A guy in Minnesota (cold) said he's had five in an empty house during some extremely cold winter nights. I absolutely love my bluebirds, especially the one that OH had to push back into the nest box so mom could feed her other three bird fledglings.