The feral pigeon (Columba livia var) is descended from the wild rock dove which inhabits both inland and sea cliffs around the Mediterranean and along the West Coast of Europe. The feral pigeon stocks are derived from many different strains of escaped ornamental, racing and domestic stocks but tend to revert to a wild type of colouring and conformation. These birds are well adapted to survive in a modern city environment where the tall buildings provide habitats very similar to the cliff homes of their ancestors.
Their natural diet is one of seeds and grains but they easily learn to exploit a large range of processed vegetable and animal products. Given an adequate food supply the pigeon can breed throughout the year and a stable pair bond is formed. Preferred nesting sites are dark enclosed areas simulating a cave or a crevice. Two eggs are usually produced and incubation is shared. Three broods may be produced by a pair each breeding season and individuals may live as long as thirty years.
Pigeon activity in and around a building may directly damage the structure as pigeons are capable of lifting roof coverings to force an entry, especially if these are already slightly displaced. This activity can allow significant water penetration into the building and subsequent decay. More seriously, they block rainwater drainage systems with their faeces (guano), feathers and other detritus. This can cause massive water penetration and severe decay problems.
Nesting activity is particularly dangerous in this respect as pigeons frequently nest in hopperheads and parapet gutters causing complete blockage in a very short time pigeon detritus and especially pigeon faeces represent both an aesthetic and a public health problem. Pigeon droppings quickly deface finishes both to the inside and outside of buildings. The presence of feral pigeons and most especially their faeces represents a potential health hazard to employees and to the general public.
They are commonly carriers of a number of serious human diseases including salmonellosis, psittacosis and pseudo-tuberculosis. Their faeces provide an ideal environment for the growth of the organisms causing such diseases as histoplasmosis, aspergillosis, cryptococcis and listeriosis. Dealing with such accumulations can be expensive and time consuming because of the protective equipment and procedures that may be required. Health and safety problems are also caused by the build up of faeces due to the slippery and unsafe footing it provides on walkways and ledges hindering proper maintenance.
