@nickdrawthing There is plenty of pee/poop, since they hold it until it's warm enough to do "cleansing flights".
In future, I'm probably going to switch to better insulation, which will help cut down on the number of bees that die, since much of this is probably bees on the outer edge of the "cliuster" they form to keep warm in winter. I've got some insulation, but probably no more than R4 or R5, and I can do better.
They still had plenty of food though, so they've been overwrintering well.