We have a total of 12 nest boxes on our property, 7 of which were SUPPOSED to be for Western Bluebirds (the Tree Swallows didn't get the memo). I checked them all today. Two boxes had clutches of 4 eggs, one had two eggs with the female on them; two were totally empty, although one of those had a couple of feathers which looked to me like Tree Swallows had explored it; one had a full next cup with no eggs. One of the boxes was commandeered by Tree Swallows right away and they are active in and around it. I didn't bother checking on the contents of that box.
We have two boxes affixed to trees, one of which was originally designed for nuthatches. Pygmy Nuthatches used it once years ago; of late it's been used by House Wrens. The other tree-mounted box has been used exclusively by House Wrens.
We have two boxes that were put up experimentally for owls. We don't check them that often because it requires us remembering where the boxes are and taking a ladder to check them. These boxes have been up for many years and have never been used for their intended purpose.
We do have one American Kestrel box that has been used by kestrels over the years. There have been some years where it wasn't used at all, and last year it was used by House Wrens. Dick Tipton put up a box for the wrens below the kestrel box in the hopes that they will use THAT one this year and not the kestrel box. No kestrels out this way yet, but I'm keeping my eyes and ears open.
In addition to the nest boxes, we have had Say's Phoebes nesting somewhere ON the house for over 10 years now. They typically use one of the logs that project from the roof line, although for a few years they built a nest on the top of our bat box which is under an eave. My husband put a platform on top of the bat box last year so they'd have a more secure place to build a nest and they did. This year they are back on a log.
And even though the House Wrens just showed up a few days ago, they are back building a nest in a soffit outside my husband's office. Brewer's Blackbirds are back building a nest in the same spruce tree as usual, just off the front lawn.