After looking at the female try out alternative cavities last night, like a lady at a shoe store, too small, too big, etc, were weren't surprised when we didn't find her tonight. I suspect she's found a nice tight cavity to stay warm in.
It is the first night in many weeks, I haven't been able to see an owl in the North Woods. It was strange. While for now, I'm sure we've just lost track of our now silent owl, it did seem to foreshadow a time when we won't have any Eastern Screech-Owls in the park.