One of the most novel and promising uses for a drone I've seen is to herd elephants away from crops and villages. Resolve has done some trials and initial results are excellent. The best low-tech solution I've seen to date is beehive fences.
The downside is that someone needs to become proficient as a drone pilot to do this effectively (unlike using drones for photography/mapping which can be done via a fixed wing drone using autopilot). Still, the auto-pilot software for quad copters are getting very sophisitcated with their "follow me" features, so it might not be long before you can draw a perimeter and a drone can automatically herd animals out of it.