One of nature's little mysteries

Steve has been working on a cabinet to be installed in the RV this week, and staining the trim was my job. I climbed up on a ladder in the shop to take down the small bucket that had the paintbrushes in and when my fingers reached down into the bucket to pick it up I ran into the strangest feeling stuff. "What the @#$% - what did he put in here?" I muttered.

Yes, I know, unfounded malicious accusations toward the beloved spouse.

I wasn't enlightened much when I finally got the bucket down on the counter and could see inside. All the brushes were intermingled with a lot of juniper bark shreds and who knows what else. What a mess. Not knowing where the bucket had been in it's recent journey from Oregon to it's shelf here in TX I could only assume the mess fell in while it was outside, or something.  I began pulling out all the paintbrushes one by one and eventually it became clear. This mess is a nest!

But whose?
And how?
And why?

After comparing notes we determined the bucket has been up on the shelf, near the door of the shop, for quite some time. The door is open during the day if we're working in there, but closed at other times, and often for many days at a time.

There were four eggs in the nest. One had been cracked and the yolk was starting to dry out, another cracked while I was rummaging around investigating and it too was moist, so the eggs were probably this season's.

The mystery is, we have never seen a bird in the shop.

Based on the eggs and style of nest I'm thinking it's a tufted titmouse, as we have a lot of them around here. Admittedly they are a small bird, but I think we'd see it at least once if one was in there often enough to lay four eggs, and there's no way in other than the doors.We see titmice outside fluttering around us all the time while they feed, so they don't seem to be a particularly bashful or secretive bird. It's a mystery!

If the bird is still around I'm afraid it's going to have to start another nest somewhere else, or it may be that this one was already abandoned and the eggs just hadn't dried out yet.

If anyone has any other theories, or suggestions of what the identity of the bird is, we'd love to hear them!