Descended originally from the Rockdove. The Romans kept semi-domesticated strains of these and the present populations of feral pigeons come from these stocks and from recent escapees of pigeon fanciers' birds. They have adapted to the roosts and nesting sites provided by buildings and other structures, and are present throughout Britain, mainly in urban environments where they depend on man for food.
The feral pigeon is about 33 cm long and weighs about 350 gms on average. Its plumage can vary from grey, blue or chequered, to almost pure black. The cock bird is usually bigger and stronger than the hen and has larger wattles.
Nests are built in or on buildings, bridges, ledges or hollows such as gutters. Grass, twigs, feathers and scraps such as pieces of wire are used in their usually rather flimsy nests. After a succession of broods the nests may become well defined. Breeding can occur throughout the year, but the peak occurs between March and July. Two white eggs are laid and incubated for 17-19 days by both parents. The young pigeons, or squabs, are fed on highly proteiniaceous pigeon milk from glands in the crop for either adult bird, but this is gradually replaced by regurgitated grain. The young are independent after 30-37 days, and up to four broods may be reared during a year. Some young birds breed at six months.
Feral Pigeons rely mainly on spillage or scraps left by the public. Some seeds may be taken from parks etc to supplement their diet. Some birds fly to arable farmland to feed on sowings and stubbles. Pigeons normally feed in flocks and can become highly efficient at taking food left unattended for short periods of time, waiting nearby until the area is undisturbed e.g. loading bays where birds will wait for lorries to move away before feeding on spillage.
Most of the damage caused by pigeons arises from their infestation of buildings where they feed on and contaminate food and machinery. From food spilled outside in loading areas, feral pigeons can transfer their attention to food in store. Fouling of buildings and monuments occurs in places where birds nest or roost.