Bob – you should have the BB during the winter. They will find shelter as they need it and may not stay in the same location on consecutive nights. I am certain that they have used my nestbox during the winter as there are a couple of down feathers, some fecal matter, and maybe a loose wing feather (blues) but I do not know when they have stayed in the box. They are always gone by the time that I am awake enough to want to go out and check.
Providing the mealworms and heated water dish will keep them in the area, but they will continue to forage the trees, woods, and brush for insects, larva, berries, etc. if it is available.
Have a great fall and winter of observing.
David
David
Stafford, VA