After my bumblebee encounter a couple of months ago, I have not disturbed the occupants of the bluebird nest box. But when the support rotted and the box was hanging upside down, I was curious to see if the bees were still there. There was no sound, so I carefully opened the door; the fluffy nest material fell out and something darted around the tree. My cat Bigboy and I discovered three baby flying squirrels on the ground, which told me the mom was the darting figure I had seen leaving. The babies had soft, velvety fur and were about 3" long plus 3" tails, with loose folds of skin on their sides.
The babies squirmed and crawled into the fluffy nest and Bigboy got bored and left. This makes me realize that the bees were not the nest builders, but squatters in the squirrel's home! I'm hopeful the mom carried the babies to a safe place, because they were gone the next morning.