Today in Canada we have a national radar system that supports most of the busier airspace in Canada. Anywhere that airspace exists, the drones could be equipped with what's called transponder technology. It's what the aircraft have, and it's why the aircraft are visible on the radar. If you equipped drones with transponders, at least in that busy corridor, you would see them in close proximity. They would show up on the radar screens immediately in the control towers.
Outside of the radar airspace and at low altitudes in proximity to the radar airspace, you wouldn't see them, but you would certainly capture the majority that exist in the busy airspace. As I mentioned earlier, new technology that has been introduced is able to detect drones within a kilometre of an aerodrome. It's basically a ground-based station that has a variety of sensing tools that are looking for drones. A kilometre is a very short distance when it comes to aircraft, but certainly it's the start of being able to monitor them.