Shooting guns at your own house may not be the image you wish to project to your neighbors or authorities... Poison can kill other animals, and pollute water sources in rain run-off. Sticky stuff "wears out" as soon as it's covered in dust.
So what works? I've noticed over the last few years a lot of commercial buildings putting this stuff where they want to deter birds from roosting/dropping things that is in essence "bird barbed wire". It is essentially a string that you nail in place that has porcupine wires sticking up at all angles (except the side you nail down). Almost invisible to the eye 20 feet away, birds hate it because there is no way for them to land on it comfortably. I've seen it on window ledges, under eaves, on the edges of roofs and even on top of columns. It won't bother neighbors or police (like guns), it won't pollute (like poison), and it won't wear out (like sticky stuff). Not sure where you would find it, but I'd try a web search...
Famous San Francisco columnist Herb Caen hated pigeons, and called them "rats with wings". HA!