In the Caribbean a big tradition every Easter is kite flying. I've landed an AStar already and on post flight found both main and tail rotor pitch links tightly wound with nylon. An R44 was brought down in Curacao because of a kite. The danger of course is you can't see the twine, and if they are using 200lb test............
And its all pretty pointless because how much of a kite can you see at 2000'?
Another danger for coastal tour pilots are the para sailors. You are over the water at 500', pointing out sights to the punters, when some competitive parasail guy decides higher is better and sticks 1000' feet of rope on to his parachute. You catch a glimpse of something out of the corner of your eye and instead of the seagull you are expecting its a peeling sunburned tourist dangling his b**locks at you..............recipe for disaster or what!!! Had to pull a seat cushion or two out of my rear end already.