We bought a propane cannon recently. It is the Zon EL08 electronically controlled version. I've fired it several times. On one occasion there was a large flock of blackbirds or maybe starlings hanging out about 200 yards away in a nearby field. I had the cannon set to the triple shot mode. On the first shot the birds all flew into the air together, then on the second shot they began to fly away. The 3rd shot went off as they were exiting the area. They flew a great distance away, far enough that I could no longer see them.
These devices can be an effective bird control tool. They appeal to the auditory senses of bird pests. Be careful in using these thunderous devices. They can be a real nuisance to neighbors (not only humans but also nearby livestock and horses). A propane cannon should be used sparingly and only when absolutely necessary. Never point them toward houses and only use them when birds are truly being a problem. If protecting vegetables or fruit, such as blueberries or strawberries, only use a propane cannon right as the produce begins to ripen. It will be much more effective. If overused, eventually the birds will no longer be scared. Just please be sure to be considerate of those living nearby. If there are any people living within 500 yards or so, it would probably be best not to use a propane cannon. For more information on bird control, check out www.scarecrow-bird-control.com!