Where Will They Now Sleep?

Later on same day of fledge, one wren, I think one of the parents, returns to the dogwood where hangs the empty house. Forlorn or bereft or relieved, I can only imagine. This wren hops around from branch to branch, singing its bubbly song. Job well done, the lyrics might as well say. Presently the wren begins to enter and exit the house repeatedly with a downy feather or tiny broken stick or tuft of dry grass in its beak---taking its cargo only as far as the first dogwood branch outside the front door, there to let it go. The brown blades flutter like chaff, the twigs drop directly to the ground, and the feathers swing away on otherwise undetectable drafts. Housecleaning. Not unlike shaking a rug.

Is it preparation for a new brood already? And what do bird books mean when they say "Fledgling period: 12-15 days?" Before this spring's observations, I would have thought the new birds continued sleeping in the nest while practicing their flying---until fully adult. Now it appears that once out they never return.

Which brings me to my years-old question: Where do adult birds sleep when not nesting? Bird books go on about mating and nesting behaviors, but I've yet to find the answer to the question of where birds sleep. The audubon birder I asked dismissed the question authoritatively without saying a damn thing. It may be a stupid question, but I still don't know the answer. Does anybody out there know? I would be humbled to hear from you. dkm