Don't read to the bottom of this post if you are against vermin destruction.
First the good news. Chris took some more photos today.
The Tree Swallows are working Bluebird Box 2. We always love these birds because they are really friendly and don't seem to mind our attentions at all. Chris got 2 photos. One with her peeking out of the box and one with her on the nest. I think they are really beautiful birds.

Then he checked on the Chickadees in the Chickadee box

and the Chickadees in Bluebird Box 4. They are getting their black caps!

You might be wondering why I am doing two bird posts in a row. I had planned to wait until Saturday to survey all of the nests again but something happened today to add "bird inventory" to Chris' list of chores.
I work at home Tuesdays and Thursdays. Today, during my lunch break, I happened to look out the window and saw a bird perched on Bluebird Box 3 (the Chickadee family photographed yesterday). I grabbed the binoculars and saw that it was the evil House Sparrow. Over our few years of birding, we have lost bird families to two things: snakes and House Sparrows. Snakes, I understand and we do a lot to dissuade them from eating our birds and, if Chris catches them in the box, they generally have an unfortunate accident.
House Sparrows are not native to the US. They are to us as the Gray Squirrel is to the Brits. (I don't like the squirrels much either but in Britain the Gray Squirrel has just about eliminated the native Red Squirrel population.) House Sparrows here are brutal to native birds. They destroy eggs and baby birds and then nest on top of the abandoned nests. I did a lot of reading on the subject last year (after they destroyed a little bluebird family) and followed the recommendation to let them lay their eggs and then destroy the nest.
When I saw the House Sparrow on the nest box I knew what had happened. I looked in the box and all of my Chickadees were gone and the Sparrow had already started building a new nest. I reported the incident to my hero hunter.
Vengeance is mine saith the bird woman....

.....followed by a full inventory of all other families.