Finally nesting again
Years ago we lived on a different part of our land and a nest box I put up attracted a pair of birds whose identity I didn't know. Turned out to be Great crested flycatchers. We enjoyed them for years but then moved to the back of our place above the river.
Put up a box to attract the flycatchers but little success until now. They have a distinctive shrill call and hearing them lately made me do some repairs to a house I've had up for a long while. Only about 40 feet from our porch to the tree the box is on.
They moved right in and are busy carrying in leaves and debris for their nest. The box is about 12- 15 ft above grade. The hole in the box is 3" diameter and the box itself is about 5 X 6 insideand 8 - 10" below the hole to the bottom. Made of weathered barn boards. Finally got em' back!
Pictures are not the best but grabbed them with my phone, these birds are pretty spooky.

The female on the perch while the male guards above.
Female with a leaf to add to her nest.
In the box for 20 seconds and ready for another trip.
I have no idea how well known these birds are or if many others try and get them to nest. Their calls are so unique you can easily tell them. Their calls carry a long way and I hear them way down in the river bottom woods.