Looks like the Owl that found the boxes in April has came back for another visit. Well its difficult to say definitively that its the same owl, but the phase is the same (gray), so my guess its the same.
Sunday October 17, first confirmed occupancy, in the slot style box.
“They (bluejays and other songbirds) have also begun to pay some attention to the owl boxes, including perching on the slotted opening and screaming into the box. It has been strangely quiet all day today, but my suspicions were confirmed. Just after the Patriots won the game, I spotted a gray morph Screech Owl in the slotted box! I couldn’t get a good look with dirty windows and lingering leaves, so I don’t know if it is the same owl that was here last April.”