A flock of pigeons has started to roost on my roof every day. Their droppings are making a mess of things. A I can tell you from personal experience that it is very difficult to get rid of pigeons. Among the most effective and commonly used deterrents, designed to keep the pigeons, sea gulls and other birds from perching on roof ridges and ledges, are strips of metal bristling with spikes. The spikes make perching too uncomfortable for the birds, and the birds move elsewhere, hopefully not on your property.
Spike strips are available in several sizes and colors.
Pigeons dislike sudden noises and movements. When I see unwelcome pigeons, I make them move on by clapping my hands briskly. A stream of water from a hose or water gun will also send pigeons packing, at least temporarily. Birdfeeders sometimes attract pigeons, especially if some of the seeds spill on the ground, where pigeons usually eat. Try to avoid spills by keeping the sides of bird feeders high.