Feral pigeon (Columba livia var)
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.
In all activities that do not involve reproduction, the pigeon is a social bird which will actively seek the company of others in order to rest, preen, and feed. They may therefore form flocks of anything from tens to hundreds of individuals, depending on the available food sources. These flocks develop a set pattern of activity, based around a defined set of feeding, resting and roosting sites. 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. The most important factor in pigeon survival is the active promotion of their population by man, for recreational and emotional reasons. This is most significant in the provision of food, and in giving protection from human predation.
The uncontrolled increase in populations of feral pigeons resulting from this commensal relationship has produced considerable problems in many city and seaport environments.
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, 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 gutters causing complete blockage in a very short time. This disruption of drainage and the resultant water penetration is especially damaging in unoccupied buildings where problems are less likely to be detected before major damage has been done. The results of water penetration are also more serious as there may already be serious damp and decay problems in the buildings. Pigeon activity of this sort can thus negate the effect of conservation and remedial work. This represents a considerable waste of time and money, and may lead to the degradation and loss of valuable building features. Though they are actively fed and encouraged by many members of the public, pigeons represent a public nuisance as well as a health hazard. This may be because of disturbance caused by calling or nesting activity in the early hours, by spreading of fleas and other parasites into inhabited buildings and by pestering for food. However, the most resented nuisance is caused by faeces.
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:
The following organisms and insects can be associated with birds, their nests and droppings:
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.
Advanced Rodent Control.