Well I for sure don’t know much about bluebirds. What I do know is that the bluebirds showed up within 1-2 weeks after the box was set up. I don’t know much history about my bluebirds other than they must have been to a bluebird boot camp somewhere. The very first season a wren family tried taking over the box and they sent them packing. They have resided in the box ever since. What would be a good guess on your part as to when to clean the nest box out since they need it for winter warmth. I know the very first season they had 2 hatchlings. I guess my question is where do the babies end up going every year that they hatch out. Somewhat clueless in Newburg Pa.