The bluebird couple that build a nest in the nestcam box have selected a Gilbertson-style nest box for their second nest. For some reason, they tend to select the Gilbertson for their second nest each season.
It is a good idea to put some pine straw near the nest box when you start to see interest on the part of the bluebirds. The availability of pine straw facilitates the nest building step.
I have started putting all my nest boxes on concrete pedestals so they can be relocated as needed. I like to place an Internet enabled color camera near the selected nest box so the nesting activity can be observed.
Bluebirds can build a complete nest in a Gilbertson-style nest box in 1–2 hours.