Bummer, bummer, bummer.
All the effort and all there was inside was a bushel of emty walnuts, a few good ones, and maybe 4 dozen bees.

I am thinking now that these may have been scouts. I cleaned the thing out and went and brought it back to the old feller I was doing this for. I told him I had cleaned it out and I left the screen on the front to prevent any stragglers from trying to get back in.
In the time it took me to put this back in the tree, there were another few dozen bees there trying to get in.

What I decided to do was I took a 5 frame nuc, put 5 medium frames with comb in it, and set it right on top of the squirrel house. Within seconds bees were going into the nuc.
I can only guess that this squirrel house is on the short list of a swarm hanging somewhere. The bees showing up with interest is huge!
Maybe I'll get lucky.