Like other owls the Northern Saw-whet doesn’t build a nest in which to use. They rely on other birds like the Northern Flicker and Pileated Woodpecker to do all the work then will use the location.
They will also take advantage of the nest boxes that we humans build for Wood Ducks…wonder what the ducks will think about that on their return ?
Hopefully the nest box will be used as it’s in a very public place with lots of human traffic.
I’ve opted not to return because of the location…good luck little owls.