Pigeons can cause structural damage, disease and defacement if they are allowed to roost on buildings. In order to get rid of them, you have to understand their habits.
Feral pigeons (Columba livia) are descendants of the wild rock dove, a bird that inhabits the cliffs around the west European and Mediterranean coastlines.
In Britain, pure-bred rock doves are only found on some Scottish coastlines.
The ancient Egyptians originally domesticated pigeons, and these have now spread worldwide due to their popularity for racing, being used as message couriers during wars, for display or simply kept them as pets.
Some of these birds escape or get lost and join existing feral flocks that are already well suited to life in our towns and cities. Our tall buildings, with their various ledges, sills, voids, pipework and recesses, provide ideal alternatives to the sites used by their ancestors on the inland or sea cliffs.
Feral pigeons are very social birds. You will find them living in flocks ranging from single figures up to hundreds of birds, depending on the availability of food and shelter.
Given these key elements, a pair of pigeons can breed all year round, although the peak period is between March and July.
The birds themselves, their nests and faeces will harbour various types of insect pests, such as fleas, flies, mites and ticks. These often cause nuisance or irritation to building occupants, and will in turn attract larger predatory insects that feed off them.
Of more serious impact is the risk of human illness caused by bacteria living within the birds' guts or their fouling.
Although there is a relatively low risk of infection from pigeons, the diseases are serious, and include Salmonellosis, Cryptococcus, Ornithosis and E. coli.
Structural damage to buildings is commonplace wherever pigeons have roosted over a period of time, especially on vacant buildings where their activities can go unnoticed for many months or years.
Blockages of gutters or rainwater pipes caused by bird fouling and/or nesting material being washed down with rainwater can cause internal flooding or damp and decay problems. Their roosting on stone features, ledges or sills on elevations can cause aesthetic issues, with fouling smearing the elevations and the ground below, teamed with the increased need for cleaning and maintenance The installation of plant equipment on the outside of office blocks, retail outlets, etc, is often of great attraction to pigeons seeking safe, warm shelter. This is turn can hinder maintenance work, as workmen can quite rightly refuse to work on bird-fouled machinery and equipment.
PHYSICAL DETERRENT METHODS There are three proven methods of deterring pigeons and some other pest birds from any part of a building or structure - the sprung wires, netting systems and spikes that are commonly seen on virtually any high street in the country. Steel weldmesh is also used, either on its own or in conjunction with other systems.
Several variants of the sprung-wire system and spikes are available to allow fitment to many different surfaces, including gutter lips, pipes or handrails, outward-opening windows and beams. With the right knowledge and experience it is possible to further customise the sprungwire system and fabricate many types of supporting brackets for nets to allow a discreet, long-lasting proofing solution to almost any kind of building or feature.
There are, of course, some cases where installing physical deterrent systems is not practical, perhaps due to the bird activity being spread over a wide area (such as town centres or housing estates), budgetary constraints or for aesthetic appeal.
The next stage therefore would be looking to reduce the number of pigeons on site by means of flock reduction or scaring them away, perhaps by using birds of prey. Using dummy birds of prey on sites is only ever effective for a short period of time (measured in weeks) because the pigeons soon realise they are not a threat. Similarly, sonic deterrents are not overly effective because the pigeons will learn to ignore the disturbance.