A new drone from Japan's largest security company Secom can chase and follow intruders on property all on its own. It does it slowly, mind you (top speed is just 10km/h or 6MPH), but it's an important innovation for interested property owners, and should be plenty sufficient before the intruder becomes aware of the drone, if they do at all.
The drone flies between three and five meters above ground and can detect suspicious vehicles and people and can send photographs it takes to a monitoring center, making security much more efficient at a given facility. It's advanced enough that it will attempt to photograph license plates and faces when possible.
The drone's dedicated launch pad and recharging system costs ¥800,000 ($6,575 USD); the drone itself can be rented for ¥5,000 (about $40 USD).