Use of Aerial Surveillance with Livestock (Score 1)

I recently attended a talk about the use of drones to monitor livestock. Although the concept seems great for observing livestock that are in hard to access areas, do you think that this could eventually be as useful as going out to monitor the animals in person? Because livestock are all prey species, they tend to hide signs of illness or distress pretty well, and I'm not sure that subtle signs would be able to be detected with the use of drones alone.