Since the 1940's, pest control companies have approached pigeon issues as a problem with the environment. Based on this core philosophy, companies began selling products to modify the environment as a means of deterring pigeons. Desperate people trusted the purveyors of these products and the industry profited. Unfortunately, these "environmental" products (spikes, nets, screens and other passive exclusions) have failed to reduce pigeon populations in the more than 60 years they have been in use. In fact, moving pigeons from place to place is a major factor as to why pigeon populations are now completely out of control in North America and around the world.
It is time to abandon all conventional thinking and approach the problem from an entirely new perspective.
Pigeons are flock animals completely dependent on a social system of sustenance and perpetuation. Like many social animals, each member plays a particular role in that social organization. When a vacancy appears in that system, other members act quickly to fill it in.
Any significant reduction in flock numbers will trigger Accelerated Replacement Breeding which will cause the pigeons to populate 4 times faster than normal. The social nature of pigeons offers a compelling explanation as to why "spot treatments" or partial removal operations always fail.
Total Exodus Theory states that in order to obtain complete control of an environment, all members of the resident flock must be removed entirely from their adopted environment. If no reproductive core is present, remaining birds will seek out and join another flock.
Now that this flock is gone, what keeps a new one from moving in?
The reason you have a pigeon problem is also the reason you won't just inherit someone else's. Pigeon patterns are fixed. Day after day, those patterns are repeated over and over in the same environment. That also means that a different flock of pigeons living somewhere else is locked into their pattern.
Pattern Suspension Theory states that if a flock is completely removed from an environment, other pigeons in other patterns will be completely unaware of the vacancy.
Eventually, as the borders of nearby flocks encroach on the cleared environment, pigeons may start to return. With monthly maintenance, these issues can be quickly resolved before the problem gets worse.