Saw them at the box about two weeks ago while it was still nice and warm. These are a brighter blue than those we have in the spring. Not sure if its the same ones with winter plumage or a different family. The bluebirds in the spring are not aggressive in protecting their young but these winter birds will dive bomb you ! May try for pics later.
How fascinating ! I do hope that you get some foto's. I find bluebirds such lovely creatures. We do not have them here.