Well, we have had nice fall weather but winter is on the horizon and yesterday hubby and I got our boxes ready. I leave my boxes up all winter in case the birds decide to roost in them when the cold comes. Usually my bluebirds find pine trees, etc, and do not use my boxes in the winter. BUT, last year was bitter and they decided to use them to keep warm. I had not prepared the boxes for this and I found two of my bluebirds ( believe the mama and papa) dead in their favorite box. This had NEVER EVER happened and I was heartbroken. SO . . . this year I decided to winterize the boxes by putting a second floor in them and closing up the air vents almost all the way (just barely enough open for some light). I had read this I believe on the Sialis.org website. Hope this helps – just letting everyone know this is a recommended duty.