If someone decided to solve this, it should be relatively easy to do. The things are hovering for three hours, which means whoever is controlling them is within the range radius of the controller. Using that as a starting point, radio detection units should be able to triangulate on the source(s). The military certainly has such capabilities on multiple platforms. FLIR equipped choppers could also help pinpoint whoever is controlling them, assuming they are out in some remote area watching their drones. Doubt any agency would commit such resources until someone determines there is a law being broken, however.