A New Turn at the Bluebird Box

The soap opera at the post bluebird box has gotten a great deal more interesting. Over two weeks a fair amount of new material went in. In three days, much of that material has now disappeared. Not just pulled out and dropped. Utterly removed to parts unknown. Trouble is, I haven't firmly identified the perpetrator nor the "plan." I have seen a male bluebird at the box, twice. But I can't tell if the bird ever was in the box, and at no time did I see the bluebird removing nest material. So we have two scenarios: (1) a putative wren nest is being dismantled and reformed as something else, or (2) the bluebirds (?) are pilfering nest material. I am watching the fun daily. And just perhaps we'll have a solution soon.