Yes, they are only investigating. My blues are doing the same thing – checking out the box for roosting or just checking it out. True scouting will begin in February, or even January, depending on the weather. At least here in Missouri, that’s what they do. You know, the male will usually pick out a box, BUT the female has to approve it, and that sometimes takes time (ha, ha)!! I agree with Cher about the placement of your “perch” – don’t what others to chase away the blues. The bluebirds will usually find some kind of natural perch – overhead utility lines, trees, buildings, etc.