Pigeon deterrents, such as "scare-owls" and spikes, can make your roof unpleasant for pigeons and keep them from landing on your roof it. Blocking access to areas where they can build a nest on or near the roof also helps keep them away.
Pigeons are scared of owls, so a fake owl placed on or near the roof line often scares pigeons away. You can also keep pigeons off the roof by placing spikes on any area where pigeons like to land. Professional strips of spikes can be installed to keep birds off the roof, or you can make your own spike strips by attaching nails, sharp side up, to a piece of wood and then placing it on the pigeon-congregating areas of your roof.
Another way to keep pigeons off your roof is by blocking access to any area around the roof that would work for a nest. If there is nowhere to make a nest, pigeons move on to the next roof. Your local animal control office can inform you of the most humane and effective methods to address your pigeon problem. They remove any pigeons on your roof at the time of their visit, and they also explain your options and local laws around the process.