The Pigeon Feral pigeon, Columbia livia vartitle

Associated Problems
The fouling of buildings and monuments frequently occurs at places where they roost and nest. The acidic droppings react with chemicals in the stonework causing erosion of the surfaces. Accumulations of droppings can become infested with mites and insects, which are pests of stored products and houses.
They carry many diseases and can give rise to the following:
Other problems include
These problems lead to increased costs of maintenance and risk of nuisance to neighbouring properties.
Large numbers of roosting pigeons also give rise to odour and noise complaints, not to mention the risk to health and safety in terms of slipping hazards on pavements and fire escapes from accumulations of droppings.
Control
There are numerous techniques available to combat feral pigeon problems. Handling a pigeon infestation most often requires a combination of products and techniques. Coil, spring wire or bird point all have distinct merits for ledge applications. For exclusion, two inch netting is sufficient, we use only woven and knotted netting for large applications. Any exclusion work should be coupled with some form of flock dispersal such as trapping or shooting. Flock reduction alone is not a long term solution as long as food and attractive shelter remain at the site.