I finally got around to cleaning out several “bluebird” (really House Wren) boxes today and found, along with all the sticks and two soft nests, a few surprises:
two very upset mice
one snake skin
one fossilized wren egg - tiny and delicate, a little smaller at its widest end than the diameter of a dime
I also discovered that one box had rotted right through, so it’s clearly time for a new one!