If someone could develop a chemical sensor as sensitive as a canine's that could be put on a drone along with the video. Find a smell that's "familiar" and follow it. Better if you can do that at a height with better lne-of-sight and able to skim above the brush and then immediately twist 180 degrees when the smell is lost. just a wild out-of-the-box thought. It's early, time for coffee -- there's a great smell, I wonder how far away a dog can smell coffee...