David, probably a good thing they have not laid eggs yet – We have had one hard freeze last week here in mid-Missouri and another freeze forecast for tonight and Monday night. I don’t have much hopes my 5 BB eggs will survive, but if mama stays on the nest incubating them good, maybe . . . .
In regard to your removing the nest – it might be wise to leave it alone unless you really are sure it was made on top of another, but from your pictures, they started from the bottom. Not sure. Maybe they know it is too cold yet, huh? Believe mine got in a hurry.
Went back and checked the nestbox after a major wind and rain event. The top edge of the nest is at or above the entry hole. There is a definite layer line where it appears that they have built on another nest. If I remove that lower level it will put the upper nest right where all of the other nests have been. I will give them tomorrow morning and if an egg does’t appear I will lower their nest and see if that makes them comfortable.
David, sounds like you have determined it is a nest on top of another nest – your plan to remove the bottom half sounds like a good idea – it would sure not work if the top edge is at the entry hole!! Good luck.