Just a quick update. A couple of days after the TRES built a beautiful nest including a nice feather lining a male bluebird began spending each morning on top of their nest box. Their high speed passes didn’t seem to phase him one bit. He also spent a good amount of time on the very top of the flagpole. Long story short, the mate he eventually found has been incubating their 4 eggs for the past 3 days in a very deep TRES constructed nest. I need to use a mirror to look down into it. They did remove the feather lining but did not alter the shape of the nest at all.
I hoped that the TRES might move to the second box I put up ~ 15 feet away but they took off to parts unknown.