I have a big Pigeon and stray cat problem at my place. The Pigeons are crapping all over my roof, and the cats all along the side of my house. So I decided to do something about it. First I went up on the roof with a broom and a hose. You wouldn't believe the amount of Pigeon $h!t that was up there! I broomed off several
POUNDS of it. Because it is so dry out here, the stuff breaks apart easily, and sweeps off like pea gravel. Then I started in with the hose. After I was through, and had everything washed and cleaned off, there was at least a pile 10" high completely across my sidewalk! It was years worth.
I used a big dustpan to shovel most of it up into a garbage can lined with 2 trash bags, so they wouldn't leak. Then hosed everything that was left into the gravel. I also picked up all of the cat $h!t along the side of my house. I went to Lowe's and bought 2 of these:
https://www.lowes.com/pd/Dalen-Great-Horned-Owl-Scarecrow-Bird-Repellent-Decoy/1000124947I filled the base with about 10 pounds of lead shot so they wouldn't blow away, and epoxied the plug shut. And then set them on my block wall on each side of the house. They really look menacing. There hasn't been a cat around since. I also was looking on Amazon and saw these, so I bought 4 of them. (Link at the bottom). I hung 2 in front, and 2 in the backyard. They really work well. They reflect sunlight with a prism like effect, in a bunch of different colors. It supposedly screws up their ability to navigate. Which in turn frightens the hell out of them. They leave the area, and are afraid to return.
So far, so good. I see them on the neighbor's roof, and on the roofs across the street. But not on mine. I couldn't believe how much crap was up there. You don't really notice it until you get up there and start removing it. If they ever come back, I'll start in with the spikes and the pellet gun. I've got 2. A 5 MM Sheridan, and a 5 MM Chinese. Both are accurate enough to hit Pigeons without cracking any roof tiles.
https://www.amazon.com/Bird-Blinder-Reflective-Hanging-Owl/dp/B01LXTO87M/ref=sr_1_10?ie=UTF8&qid=1493035467&sr=8-10-spons&keywords=pidgeon+repellant&psc=1