In the case of pigeons, prevention is the best strategy for control. Keeping food sources in bird proof storage and feeders is key. Promptly cleaning up spilled food or garbage will help prevent attracting birds. Also, prevent easy access to water by maintaining the water level in livestock waterers so it is too deep for birds to stand in it, yet shallow enough that if a bird were perched on the edge of the waterer that it would be unable to drink.
Creating barriers for entry into structures is also critical. Methods that can be used include hanging plastic strips in doorways that allow people, larger animals, and machinery to pass through, but prevent birds from easy flight patterns into the building. Also, close all openings that exceed half of an inch. It is very important, but often overlooked to cover openings to lofts, vents, and eaves with wood, metal, glass, or wire mesh. Open or broken windows should also be addressed. Birds can also be discouraged from roosting in rafters by hanging netting beneath them.
Once pigeons have become comfortable in a space it is difficult to remove them. A combination of techniques will likely need to be used. These include modifying potential roosting sights to have a slope greater than 45 degrees, porcupine wires, electrical conductors that shock birds when they land on perches, and/or chemical perch repellents.
Slowing the reproductive rate is also important. Pigeons can breed all year round with peak brooding time in the spring and fall. They will lay eggs almost anywhere on sparse nests. The eggs can be destroyed. It will take monitoring and action every two weeks to prevent nesting. Trapping birds is another option that can be pursued with pre-baited live traps. Caught birds can then be relocated and released (permission must be granted at the release site) or euthanized. Lethal methods may be used, but issues with actions that may be prohibited in residential spaces and potential off target deaths are concerning. Thus, deterring birds from becoming comfortable in a space is the best plan of action. Help with extermination can be sought from licensed nuisance animal control professionals if necessary.
Source : osu.edu